Contact Dermatitis

In 2023, ESPEN (the European Society for Clinical Nutrition and Metabolism) published consensus recommendations highlighting the importance of regular monitoring and treatment of nutrient deficiencies in patients with inflammatory bowel disease (IBD) for improved prognosis, mortality, and quality of life.¹ Suboptimal nutrition in patients with IBD predominantly results from inflammation of the gastrointestinal (GI) tract leading to malabsorption; however, medications commonly used to manage IBD also can contribute to malnutrition.^2,3 Additionally, patients may develop nausea and food avoidance due to medication or the disease itself, leading to nutritional withdrawal and eventual deficiency.⁴ Even with the development of diets focused on balancing nutritional needs and decreasing inflammation,⁵ offsetting this aversion to food can be difficult to overcome.²

Cutaneous manifestations of IBD are multifaceted and can be secondary to the disease, reactive to or associated with IBD, or effects from nutritional deficiencies. The most common vitamin and nutrient deficiencies in patients with IBD include iron; zinc; calcium; vitamin D; and vitamins B₆ (pyridoxine), B₉ (folic acid), and B₁₂.⁶ Malnutrition may manifest with cutaneous disease, and dermatologists can be the first to identify and assess for nutritional deficiencies. In this article, we review the mechanisms of these micronutrient depletions in the context of IBD, their subsequent dermatologic manifestations (Table), and treatment and monitoring guidelines for each deficiency.

Iron

A systematic review conducted from 2007 to 2012 in European patients with IBD (N=2192) found the overall prevalence of anemia in this population to be 24% (95% CI, 18%-31%), with 57% of patients with anemia experiencing iron deficiency.⁷ Anemia is observed more commonly in patients hospitalized with IBD and is common in patients with both Crohn disease and ulcerative colitis.⁸

Pathophysiology—Iron is critically important in oxygen transportation throughout the body as a major component of hemoglobin. Physiologically, the low pH of the duodenum and proximal jejunum allows divalent metal transporter 1 to transfer dietary Fe³⁺ into enterocytes, where it is reduced to the transportable Fe²⁺.^9,10 Distribution of Fe²⁺ ions from enterocytes relies on ferroportin, an iron-transporting protein, which is heavily regulated by the protein hepcidin.¹¹ Hepcidin, a known acute phase reactant, will increase in the setting of active IBD, causing a depletion of ferroportin and an inability of the body to utilize the stored iron in enterocytes.¹² This poor utilization of iron stores combined with blood loss caused by inflammation in the GI tract is the proposed primary mechanism of iron-deficiency anemia observed in patients with IBD.¹³

Cutaneous Manifestations—From a dermatologic perspective, iron-deficiency anemia can manifest with a wide range of symptoms including glossitis, koilonychia, xerosis and/or pruritus, and brittle hair or hair loss.^14,15 Although the underlying pathophysiology of these cutaneous manifestations is not fully understood, there are several theories assessing the mechanisms behind the skin findings of iron deficiency.

Atrophic glossitis has been observed in many patients with iron deficiency and is thought to manifest due to low iron concentrations in the blood, thereby decreasing oxygen delivery to the papillae of the dorsal tongue with resultant atrophy.^16,17 Similarly, decreased oxygen delivery to the nail bed capillaries may cause deformities in the nail called koilonychia (or “spoon nails”).¹⁸ Iron is a key co-factor in collagen lysyl hydroxylase that promotes collagen binding; iron deficiency may lead to disruptions in the epidermal barrier that can cause pruritus and xerosis.¹⁹ An observational study of 200 healthy patients with a primary concern of pruritus found a correlation between low serum ferritin and a higher degree of pruritus (r=−0.768; P<.00001).²⁰

Evidence for iron’s role in hair growth comes from a mouse model study with a mutation in the serine protease TMPRSS6—a protein that regulates hepcidin and iron absorption—which caused an increase in hepcidin production and subsequent systemic iron deficiency. Mice at 4 weeks of age were devoid of all body hair but had substantial regrowth after initiation of a 2-week iron-rich diet, which suggests a connection between iron repletion and hair growth in mice with iron deficiency.²¹ Additionally, a meta-analysis analyzing the comorbidities of patients with alopecia areata found them to have higher odds (odds ratio [OR]=2.78; 95% CI, 1.23-6.29) of iron-deficiency anemia but no association with IBD (OR=1.48; 95% CI, 0.32-6.82).²²

Diagnosis and Monitoring—The American Gastroenterological Association recommends a complete blood cell count (CBC), serum ferritin, transferrin saturation (TfS), and C-reactive protein (CRP) as standard evaluations for iron deficiency in patients with IBD. Patients with active IBD should be screened every 3 months,and patients with inactive disease should be screened every 6 to 12 months.²³

Although ferritin and TfS often are used as markers for iron status in healthy individuals, they are positive and negative acute phase reactants, respectively. Using them to assess iron status in patients with IBD may inaccurately represent iron status in the setting of inflammation from the disease.²⁴ The European Crohn’s and Colitis Organisation (ECCO) produced guidelines to define iron deficiency as a TfS less than 20% or a ferritin level less than 30 µg/L in patients without evidence of active IBD and a ferritin level less than 100 µg/L for patients with active inflammation.²⁵

A 2020 multicenter observational study of 202 patients with diagnosed IBD found that the ECCO guideline of ferritin less than 30 µg/L had an area under the receiver operating characteristic (AUROC) curve of 0.69, a sensitivity of 0.43, and a specificity of 0.95 in their population.²⁶ In a sensitivity analysis stratifying patients by CRP level (<10 or ≥10 mg/L), the authors found that for patients with ulcerative colitis and a CRP less than 10 mg/L, a cut-off value of ferritin less than 65 µg/L (AUROC=0.78) had a sensitivity of 0.78 and specificity of 0.76, and a TfS value of less than 16% (AUROC=0.88) had a sensitivity of 0.79 and a specificity of 0.9. In patients with a CRP of 10 mg/L or greater, a cut-off value of ferritin 80 µg/L (AUROC=0.76) had a sensitivity of 0.75 and a specificity of 0.82, and a TfS value of less than 11% (AUROC=0.69) had a sensitivity of 0.79 and a specificity of 0.88. There were no ferritin cut-off values associated with good diagnostic performance (defined as both sensitivity and specificity >0.70) for iron deficiency in patients with Crohn disease.²⁶

The authors recommended using an alternative iron measurement such as soluble transferrin receptor (sTfR)/log ferritin ratio (TfR-F) that is not influenced by active inflammation and has a good correlation with ferritin values (TfR-F: r=0.66; P<.001).²⁶ However, both sTfR and TfR-F have high costs and intermethod variability as well as differences in their reference ranges depending on which laboratory performs the analysis, limiting the accessibility and practicality of easily obtaining these tests.²⁷ Although there may be inaccuracies for standard ferritin or TfS under ECCO guidelines, proposed alternatives have their own limitations, which may make ferritin and TfS the most reasonable evaluations of iron status as long as disease activity status at the time of testing is taken into consideration.

Treatment—Treatment of underlying iron deficiency in patients with IBD requires reversing the cause of the deficiency and supplementing iron. In patients with IBD, the options to supplement iron may be limited by active disease, making oral intake less effective. Oral iron supplementation also is associated with notable GI adverse effects that may be exacerbated in patients with IBD. A systematic review of 43 randomized controlled trials (RCTs) evaluating GI adverse effects (eg, nausea, abdominal pain, diarrhea, constipation, and black or tarry stools) of oral ferrous sulfate compared with placebo or intravenous (IV) iron supplementation in healthy nonanemic individuals found a significant increase in GI adverse effects with oral supplementation (placebo: OR=2.32; P<.0001; IV: OR=3.05; P<.0001).²⁸

Therefore, IV iron repletion may be necessary in patients with IBD and may require numerous infusions depending on the formulation of iron. In an RCT conducted in 2011, patients with iron-deficiency anemia with quiescent or mild to moderate IBD were treated with either IV iron sulfate or ferric carboxymaltose.²⁹ With a primary end point of hemoglobin response greater than 2 g/dL, the authors found that 150 of 240 patients responded to ferric carboxymaltose vs 118 of 235 treated with iron sulfate (P=.004). The dosing for ferric carboxymaltose was 1 to 3 infusions of 500 to 1000 mg of iron and for iron sulfate up to 11 infusions of 200 mg of iron.²⁹

Zinc

A systematic review of zinc deficiency in patients with IBD identified 7 studies including 2413 patients and revealed those with Crohn disease had a higher prevalence of zinc deficiency compared with patients with ulcerative colitis (54% vs 41%).³⁰

Pathophysiology—Zinc serves as a catalytic cofactor for enzymatic activity within proteins and immune cells.³¹ The homeostasis of zinc is tightly regulated within the brush border of the small intestine by zinc transporters ZIP4 and ZIP1 from the lumen of enterocytes into the bloodstream.³² Inflammation in the small intestine due to Crohn disease can result in zinc malabsorption.

Ranaldi et al³³ exposed intestinal cells and zinc-depleted intestinal cells to tumor necrosis factor α media to simulate an inflammatory environment. They measured transepithelial electrical resistance as a surrogate for transmembrane permeability and found that zinc-depleted cells had a statistically significantly higher transepithelial electrical resistance percentage (60% reduction after 4 hours; P<1.10^–6) when exposed to tumor necrosis factor α signaling compared with normal intestinal cells. They concluded that zinc deficiency can increase intestinal permeability in the presence of inflammation, creating a cycle of further nutrient malabsorption and inflammation exacerbating IBD symptoms.³³

Cutaneous Manifestations—After absorption in the small intestine, approximately 5% of zinc resides in the skin, with the highest concentration in the stratum spinosum.³⁴ A cell study found that keratinocytes in zinc-deficient environments had higher rates of apoptosis compared with cells in normal media. The authors proposed that this higher rate of apoptosis and the resulting inflammation could be a mechanism for developing the desquamative or eczematous scaly plaques that are common cutaneous manifestations of zinc deficiency.³⁵

Other cutaneous findings may include angular cheilitis, stomatitis, glossitis, paronychia, onychodystrophy, generalized alopecia, and delayed wound healing.³⁶ The histopathology of these skin lesions is characterized by granular layer loss, epidermal pallor, confluent parakeratosis, spongiosis, dyskeratosis, and psoriasiform hyperplasia.³⁷

Diagnosis and Monitoring—Assessing serum zinc levels is challenging, as they may decrease during states of inflammation.³⁸ A mouse model study showed a 3.1-fold increase (P<.001) in ZIP14 expression in wild-type mice compared with an IL-6 -/- knock-down model after IL-6 exposure. The authors concluded that the upregulation of ZIP14 in the liver due to inflammatory cytokine upregulation decreases zinc availability in serum.³⁹ Additionally, serum zinc can overestimate the level of deficiency in IBD because approximately 75% of serum zinc is bound to albumin, which decreases in the setting of inflammation.^40-42

Alternatively, alkaline phosphatase (AP), a zinc-dependent metalloenzyme, may be a better evaluator of zinc status during periods of inflammation. A study in rats evaluated zinc through serum zinc levels and AP levels after a period of induced stress to mimic a short-term inflammatory state.⁴³ The researchers found that total body stores of zinc were unaffected throughout the experiment; only serum zinc declined throughout the experiment duration while AP did not. Because approximately 75% of serum zinc is bound to serum albumin,⁴² the researchers concluded the induced inflammatory state depleted serum albumin and redistributed zinc to the liver, causing the observed serum zinc changes, while total body zinc levels and AP were largely unaffected in comparison.⁴³ Comorbid conditions such as liver or bone disease can increase AP levels, which limits the utility of AP as a surrogate for zinc in patients with comorbidities.⁴⁴ However, even in the context of active IBD, serum zinc still is currently considered the best biomarker to evaluate zinc status.⁴⁵

Treatment—The recommended dose for zinc supplementation is 20 to 40 mg daily with higher doses (>50 mg/d) for patients with malabsorptive syndromes such as IBD.⁴⁶ It can be administered orally or parenterally. Although rare, zinc replacement therapy may be associated with diarrhea, nausea, vomiting, mild headaches, and fatigue.⁴⁶ Additional considerations should be taken when repleting other micronutrients with zinc, as calcium and folate can inhibit zinc reabsorption, while zinc itself can inhibit iron and copper reabsorption.⁴⁷

Vitamin D and Calcium

Low vitamin D levels (<50 nmol/L) and hypocalcemia (<8.8 mg/dL) are common in patients with IBD.^48,49

Pathophysiology—Vitamin D levels are maintained via 2 mechanisms. The first mechanism is through the skin, as keratinocytes produce 7-dehydrocholesterol after exposure to UV light, which is converted into previtamin D₃ and then thermally isomerizes into vitamin D₃. This vitamin D₃ is then transported to the liver on vitamin D–binding protein.⁵⁰ The second mechanism is through oral vitamin D₃ that is absorbed through vitamin D receptors in intestinal epithelium and transported to the liver, where it is hydroxylated into 25-hydroxyvitamin D (25[OH]D), then to the kidneys for hydroxylation to 1,25(OH)₂D for redistribution throughout the body.⁵⁰ This activated form of vitamin D regulates calcium absorption in the intestine, and optimal vitamin D levels are necessary to absorb calcium efficiently.⁵¹ Inflammation from IBD within the small intestine can downregulate vitamin D receptors, causing malabsorption and decreased serum vitamin D.⁵²

Vitamin D signaling also is vital to maintaining the tight junctions and adherens junctions of the intestinal epithelium. Weakening the permeability of the epithelium further exacerbates malabsorption and subsequent vitamin D deficiency.⁵² A meta-analysis of 27 studies including 8316 patients with IBD showed low vitamin D levels were associated with increased odds of disease activity (OR=1.53; 95% CI, 1.32-1.77), mucosal inflammation (OR=1.25; 95% CI, 1.06-1.47), and future clinical relapse (OR=1.23; 95% CI, 1.03-1.47) in patients with Crohn disease. The authors concluded that low levels of vitamin D could be used as a potential biomarker of inflammatory status in Crohn disease.⁵³

Vitamin D and calcium are further implicated in maintaining skeletal health,⁴⁷ while vitamin D specifically helps maintain intestinal homeostasis⁵⁴ and immune system modulation in the skin.⁵⁵

Cutaneous Manifestations—Vitamin D is thought to play crucial roles in skin differentiation and proliferation, cutaneous innate immunity, hair follicle cycling, photoprotection, and wound healing.⁵⁶ Vitamin D deficiency has been observed in a large range of cutaneous diseases including skin cancer, psoriasis, vitiligo, bullous pemphigoid, atopic dermatitis, and various types of alopecia.^56-59 It is unclear whether vitamin D deficiency facilitates these disease processes or is merely the consequence of a disrupted cutaneous surface with the inability to complete the first step in vitamin D processing. A 2014 meta-analysis of 290 prospective cohort studies and 172 randomized trials concluded that 25(OH)D deficiency was associated with ill health and did not find causal evidence for any specific disease, dermatologic or otherwise.⁶⁰ Calcium deficiency may cause epidermal changes including dry skin, coarse hair, and brittle nails.⁶¹

Diagnosis and Monitoring—The ECCO guidelines recommend obtaining serum 25(OH)D levels every 3 months in patients with IBD.⁶² Levels less than 75 nmol/L are considered deficient, and a value less than 30 nmol/L increases the risk for osteomalacia and nutritional rickets, constituting severe vitamin D deficiency.^63-65

An observational study of 325 patients with IBD showed a statistically significant negative correlation between serum vitamin D and fecal calprotectin (r=−0.19; P<.001), a stool-based marker for gut inflammation, supporting vitamin D as a potential biomarker in IBD.⁶⁶

Evaluation of calcium can be done through serum levels in patients with IBD.⁶⁷ Patients with IBD are at risk for hypoalbuminemia; therefore, consideration should be taken to ensure calcium levels are corrected, as approximately 50% of calcium is bound to albumin or other ions in the body,⁶⁸ which can be done by adjusting the calcium concentration by 0.02 mmol/L for every 1 g/L of albumin above or below 40 g/L. In the most critically ill patients, a direct ionized calcium blood level should be used instead because the previously mentioned correction calculations are inaccurate when albumin is critically low.⁶⁹

Treatment—The ECCO guidelines recommend calcium and vitamin D repletion of 500 to 1000 mg and 800 to 1000 U, respectively, in patients with IBD on systemic corticosteroids to prevent the negative effects of bone loss.⁶² Calcium repletion in patients with IBD who are not on systemic steroids are the same as for the general population.⁶⁵

Vitamin D repletion also may help decrease IBD activity. In a prospective study, 10,000 IU/d of vitamin D in 10 patients with IBD—adjusted over 12 weeks to a target of 100 to 125 nmol/L of serum 25(OH)D—showed a significant reduction in clinical Crohn activity (P=.019) over the study period.⁷⁰ In contrast, 2000 IU/d for 3 months in an RCT of 27 patients with Crohn disease found significantly lower CRP (P=.019) and significantly higher self-reported quality of life (P=.037) but nonsignificant decreases in Crohn activity (P=.082) in patients with 25(OH)D levels of 75 nmol/L or higher compared with those with 25(OH)D levels less than 75 nmol/L.⁷¹

These discrepancies illustrate the need for expanded clinical trials to elucidate the optimal vitamin D dosing for patients with IBD. Ultimately, assessing vitamin D and calcium status and considering repletion in patients with IBD, especially those with comorbid dermatologic diseases such as poor wound healing, psoriasis, or atopic dermatitis, is important.

Vitamin B₆ (Pyridoxine)

Pathophysiology—Pyridoxine is an important coenzyme for many functions including amino acid transamination, fatty acid metabolism, and conversion of tryptophan to niacin. It is absorbed in the jejunum and ileum and subsequently transported to the liver for rephosphorylation and release into its active form.³⁶ An observational study assessing the nutritional status of patients with IBD found that only 5.7% of 105 patients with food records had inadequate dietary intake of pyridoxine, but 29% of all patients with IBD had subnormal pyridoxine levels.⁷² Additionally, they found no significant difference in the prevalence of subnormal pyridoxine levels in patients with active IBD vs IBD in remission. The authors suggested that the subnormal pyridoxine levels in patients with IBD likely were multifactorial and resulted from malabsorption due to active disease, inflammation, and inadequate intake.⁷²

Cutaneous Manifestations—Cutaneous findings associated with pyridoxine deficiency include periorificial and perineal dermatitis,⁷³ angular stomatitis, and cheilitis with associated burning, redness, and tongue edema.³⁶ Additionally, pyridoxine is involved in the conversion of tryptophan to niacin, and its deficiency may manifest with pellagralike findings.⁷⁴

Because pyridoxine is critical to protein metabolism, its deficiency may disrupt key cellular structures that rely on protein concentrations to maintain structural integrity. One such structure in the skin that heavily relies on protein concentrations is the ground substance of the extracellular matrix—the amorphous gelatinous spaces that occupy the areas between the extracellular matrix, which consists of cross-linked glycosaminoglycans and proteins.⁷⁵ Without protein, ground substance increases in viscosity and can disrupt the epidermal barrier, leading to increased transepidermal water loss and ultimately inflammation.⁷⁶ Although this theory has yet to be validated fully, this is a potential mechanistic explanation for the inflammation in dermal papillae that leads to dermatitis observed in pyridoxine deficiency.

Diagnosis and Monitoring—Direct biomarkers of pyridoxine status are in serum, plasma, erythrocytes, and urine, with the most common measurement in plasma as pyridoxal 5′-phosphate (PLP).⁷⁷ Plasma PLP concentrations lower than 20 nmol/L are suggestive of deficiency.⁷⁸ Plasma PLP has shown inverse relationships with acute phase inflammatory markers CRP⁷⁹ and AP,⁷⁸ thereby raising concerns for its validity to assess pyridoxine status in patients with symptomatic IBD.⁸⁰

Alternative evaluations of pyridoxine include tryptophan and methionine loading tests,³⁶ which are measured via urinary excretion and require normal kidney function to be accurate. They should be considered in IBD if necessary, but routine testing, even in patients with symptomatic IBD, is not recommended in the ECCO guidelines. Additional considerations should be taken in patients with altered nutrient requirements such as those who have undergone bowel resection due to highly active disease or those who receive parenteral nutritional supplementation.⁸¹

Treatment—Recommendations for oral pyridoxine supplementation range from 25 to 600 mg daily,⁸² with symptoms typically improving on 100 mg daily.³⁶ Pyridoxine supplementation may have additional benefits for patients with IBD and potentially modulate disease severity. An IL-10 knockout mouse supplemented with pyridoxine had an approximately 60% reduction (P<.05) in inflammation compared to mice deficient in pyridoxine.⁸³ The authors suggest that PLP-dependent enzymes can inhibit further proinflammatory signaling and T-cell migration that can exacerbate IBD. Ultimately, more data is needed before determining the efficacy of pyridoxine supplementation for active IBD.

Vitamin B₁₂ and Vitamin B₉ (Folic Acid)

Pathophysiology—Vitamin B₁₂ is reabsorbed in the terminal ileum, the distal portion of the small intestine. The American Gastroenterological Association recommends that patients with a history of extensive ileal disease or prior ileal surgery, which is the case for many patients with Crohn disease, be monitored for vitamin B₁₂ deficiency.²³ Monitoring and rapid supplementation of vitamin B₁₂ can prevent pernicious anemia and irreversible neurologic damage that may result from deficiency.⁸⁴

Folic acid is primarily absorbed in the duodenum and jejunum of the small intestine. A meta-analysis performed in 2017 assessed studies observing folic acid and vitamin B₁₂ levels in 1086 patients with IBD compared with 1484 healthy controls and found an average difference in serum folate concentration of 0.46 nmol/L (P<.001).⁸⁴ Interestingly, this study did not find a significant difference in serum vitamin B₁₂ levels between patients with IBD and healthy controls, highlighting the mechanism of vitamin B₁₂ deficiency in IBD because only patients with terminal ileal involvement are at risk for malabsorption and subsequent deficiency.

Cutaneous Manifestations—Both vitamin B₁₂ and folic acid deficiency can manifest as cheilitis, glossitis, and/or generalized hyperpigmentation that is accentuated in the flexural areas, palms, soles, and oral cavity.^85,86 Systemic symptoms of patients with vitamin B₁₂ and folic acid deficiency include megaloblastic anemia, pallor, and fatigue. A potential mechanism for the hyperpigmentation observed from vitamin B₁₂ deficiency came from an electron microscope study that showed an increased concentration of melanosomes in a patient with deficiency.⁸⁷

Diagnosis and Monitoring—In patients with suspected vitamin B₁₂ and/or folic acid deficiency, initial evaluation should include a CBC with peripheral smear and serum vitamin B₁₂ and folate levels. In cases for which the diagnosis still is unclear after initial testing, methylmalonic acid and homocysteine levels can help differentiate between the 2 deficiencies. Methylmalonic acid classically is elevated (>260 nmol/L) in vitamin B₁₂ deficiency but not in folate deficiency.⁸⁸ Cut-off values for vitamin B₁₂ deficiency are less than 200 to 250 pg/mL forserum vitamin B₁₂ and/or an elevated level of methylmalonic acid (>0.271 µmol/L).⁸⁹ A serum folic acid value greater than 3 ng/mL and/or erythrocyte folate concentrations greater than 140 ng/mL are considered adequate, whereas an indicator of folic acid deficiency is a homocysteine level less than 10 µmol/L.⁹⁰ A CBC can screen for macrocytic megaloblastic anemias (mean corpuscular volume >100 fl), which are classic diagnostic signs of an underlying vitamin B₁₂ or folate deficiency.

Treatment—According to the Centers for Disease Control and Prevention, supplementation of vitamin B₁₂ can be done orally with 1000 µg daily in patients with deficiency. In patients with active IBD, oral reabsorption of vitamin B₁₂ can be less effective, making subcutaneous or intramuscular administration (1000 µg/wk for 8 weeks, then monthly for life) better options.⁸⁹

Patients with IBD managed with methotrexate should be screened carefully for folate deficiency. Methotrexate is a folate analog that sometimes is used for the treatment of IBD. Reversible competitive inhibition of dihydrofolate reductase can precipitate a systemic folic acid decrease.⁹¹ Typically, oral folic acid (1 to 5 mg/d) is sufficient to treat folate deficiency, with the ESPEN recommending 5 mg once weekly 24 to 72 hours after methotrexate treatment or 1 mg daily for 5 days per week in patients with IBD.¹ Alternative formulations—IV, subcutaneous, or intramuscular—are available for patients who cannot tolerate oral intake.⁹²

Final Thoughts

Dermatologists can be the first to observe the cutaneous manifestations of micronutrient deficiencies. Although the symptoms of each micronutrient deficiency discussed may overlap, attention to small clinical clues in patients with IBD can improve patient outcomes and quality of life. For example, koilonychia with glossitis and xerosis likely is due to iron deficiency, while zinc deficiency should be suspected in patients with scaly eczematous plaques in skin folds. A high level of suspicion for micronutrient deficiencies in patients with IBD should be followed by a complete patient history, review of systems, and thorough clinical examination. A thorough laboratory evaluation can pinpoint nutritional deficiencies in patients with IBD, keeping in mind that specific biomarkers such as ferritin and serum zinc also act as acute phase reactants and should be interpreted in this context. Co-management with gastroenterologists should be a priority in patients with IBD, as gaining control of inflammatory disease is crucial for the prevention of recurrent vitamin and micronutrient deficiencies in addition to long-term health in this population.

In 2023, ESPEN (the European Society for Clinical Nutrition and Metabolism) published consensus recommendations highlighting the importance of regular monitoring and treatment of nutrient deficiencies in patients with inflammatory bowel disease (IBD) for improved prognosis, mortality, and quality of life.¹ Suboptimal nutrition in patients with IBD predominantly results from inflammation of the gastrointestinal (GI) tract leading to malabsorption; however, medications commonly used to manage IBD also can contribute to malnutrition.^2,3 Additionally, patients may develop nausea and food avoidance due to medication or the disease itself, leading to nutritional withdrawal and eventual deficiency.⁴ Even with the development of diets focused on balancing nutritional needs and decreasing inflammation,⁵ offsetting this aversion to food can be difficult to overcome.²

Cutaneous manifestations of IBD are multifaceted and can be secondary to the disease, reactive to or associated with IBD, or effects from nutritional deficiencies. The most common vitamin and nutrient deficiencies in patients with IBD include iron; zinc; calcium; vitamin D; and vitamins B₆ (pyridoxine), B₉ (folic acid), and B₁₂.⁶ Malnutrition may manifest with cutaneous disease, and dermatologists can be the first to identify and assess for nutritional deficiencies. In this article, we review the mechanisms of these micronutrient depletions in the context of IBD, their subsequent dermatologic manifestations (Table), and treatment and monitoring guidelines for each deficiency.

Iron

A systematic review conducted from 2007 to 2012 in European patients with IBD (N=2192) found the overall prevalence of anemia in this population to be 24% (95% CI, 18%-31%), with 57% of patients with anemia experiencing iron deficiency.⁷ Anemia is observed more commonly in patients hospitalized with IBD and is common in patients with both Crohn disease and ulcerative colitis.⁸

Pathophysiology—Iron is critically important in oxygen transportation throughout the body as a major component of hemoglobin. Physiologically, the low pH of the duodenum and proximal jejunum allows divalent metal transporter 1 to transfer dietary Fe³⁺ into enterocytes, where it is reduced to the transportable Fe²⁺.^9,10 Distribution of Fe²⁺ ions from enterocytes relies on ferroportin, an iron-transporting protein, which is heavily regulated by the protein hepcidin.¹¹ Hepcidin, a known acute phase reactant, will increase in the setting of active IBD, causing a depletion of ferroportin and an inability of the body to utilize the stored iron in enterocytes.¹² This poor utilization of iron stores combined with blood loss caused by inflammation in the GI tract is the proposed primary mechanism of iron-deficiency anemia observed in patients with IBD.¹³

Cutaneous Manifestations—From a dermatologic perspective, iron-deficiency anemia can manifest with a wide range of symptoms including glossitis, koilonychia, xerosis and/or pruritus, and brittle hair or hair loss.^14,15 Although the underlying pathophysiology of these cutaneous manifestations is not fully understood, there are several theories assessing the mechanisms behind the skin findings of iron deficiency.

Atrophic glossitis has been observed in many patients with iron deficiency and is thought to manifest due to low iron concentrations in the blood, thereby decreasing oxygen delivery to the papillae of the dorsal tongue with resultant atrophy.^16,17 Similarly, decreased oxygen delivery to the nail bed capillaries may cause deformities in the nail called koilonychia (or “spoon nails”).¹⁸ Iron is a key co-factor in collagen lysyl hydroxylase that promotes collagen binding; iron deficiency may lead to disruptions in the epidermal barrier that can cause pruritus and xerosis.¹⁹ An observational study of 200 healthy patients with a primary concern of pruritus found a correlation between low serum ferritin and a higher degree of pruritus (r=−0.768; P<.00001).²⁰

Evidence for iron’s role in hair growth comes from a mouse model study with a mutation in the serine protease TMPRSS6—a protein that regulates hepcidin and iron absorption—which caused an increase in hepcidin production and subsequent systemic iron deficiency. Mice at 4 weeks of age were devoid of all body hair but had substantial regrowth after initiation of a 2-week iron-rich diet, which suggests a connection between iron repletion and hair growth in mice with iron deficiency.²¹ Additionally, a meta-analysis analyzing the comorbidities of patients with alopecia areata found them to have higher odds (odds ratio [OR]=2.78; 95% CI, 1.23-6.29) of iron-deficiency anemia but no association with IBD (OR=1.48; 95% CI, 0.32-6.82).²²

Diagnosis and Monitoring—The American Gastroenterological Association recommends a complete blood cell count (CBC), serum ferritin, transferrin saturation (TfS), and C-reactive protein (CRP) as standard evaluations for iron deficiency in patients with IBD. Patients with active IBD should be screened every 3 months,and patients with inactive disease should be screened every 6 to 12 months.²³

Although ferritin and TfS often are used as markers for iron status in healthy individuals, they are positive and negative acute phase reactants, respectively. Using them to assess iron status in patients with IBD may inaccurately represent iron status in the setting of inflammation from the disease.²⁴ The European Crohn’s and Colitis Organisation (ECCO) produced guidelines to define iron deficiency as a TfS less than 20% or a ferritin level less than 30 µg/L in patients without evidence of active IBD and a ferritin level less than 100 µg/L for patients with active inflammation.²⁵

A 2020 multicenter observational study of 202 patients with diagnosed IBD found that the ECCO guideline of ferritin less than 30 µg/L had an area under the receiver operating characteristic (AUROC) curve of 0.69, a sensitivity of 0.43, and a specificity of 0.95 in their population.²⁶ In a sensitivity analysis stratifying patients by CRP level (<10 or ≥10 mg/L), the authors found that for patients with ulcerative colitis and a CRP less than 10 mg/L, a cut-off value of ferritin less than 65 µg/L (AUROC=0.78) had a sensitivity of 0.78 and specificity of 0.76, and a TfS value of less than 16% (AUROC=0.88) had a sensitivity of 0.79 and a specificity of 0.9. In patients with a CRP of 10 mg/L or greater, a cut-off value of ferritin 80 µg/L (AUROC=0.76) had a sensitivity of 0.75 and a specificity of 0.82, and a TfS value of less than 11% (AUROC=0.69) had a sensitivity of 0.79 and a specificity of 0.88. There were no ferritin cut-off values associated with good diagnostic performance (defined as both sensitivity and specificity >0.70) for iron deficiency in patients with Crohn disease.²⁶

The authors recommended using an alternative iron measurement such as soluble transferrin receptor (sTfR)/log ferritin ratio (TfR-F) that is not influenced by active inflammation and has a good correlation with ferritin values (TfR-F: r=0.66; P<.001).²⁶ However, both sTfR and TfR-F have high costs and intermethod variability as well as differences in their reference ranges depending on which laboratory performs the analysis, limiting the accessibility and practicality of easily obtaining these tests.²⁷ Although there may be inaccuracies for standard ferritin or TfS under ECCO guidelines, proposed alternatives have their own limitations, which may make ferritin and TfS the most reasonable evaluations of iron status as long as disease activity status at the time of testing is taken into consideration.

Treatment—Treatment of underlying iron deficiency in patients with IBD requires reversing the cause of the deficiency and supplementing iron. In patients with IBD, the options to supplement iron may be limited by active disease, making oral intake less effective. Oral iron supplementation also is associated with notable GI adverse effects that may be exacerbated in patients with IBD. A systematic review of 43 randomized controlled trials (RCTs) evaluating GI adverse effects (eg, nausea, abdominal pain, diarrhea, constipation, and black or tarry stools) of oral ferrous sulfate compared with placebo or intravenous (IV) iron supplementation in healthy nonanemic individuals found a significant increase in GI adverse effects with oral supplementation (placebo: OR=2.32; P<.0001; IV: OR=3.05; P<.0001).²⁸

Therefore, IV iron repletion may be necessary in patients with IBD and may require numerous infusions depending on the formulation of iron. In an RCT conducted in 2011, patients with iron-deficiency anemia with quiescent or mild to moderate IBD were treated with either IV iron sulfate or ferric carboxymaltose.²⁹ With a primary end point of hemoglobin response greater than 2 g/dL, the authors found that 150 of 240 patients responded to ferric carboxymaltose vs 118 of 235 treated with iron sulfate (P=.004). The dosing for ferric carboxymaltose was 1 to 3 infusions of 500 to 1000 mg of iron and for iron sulfate up to 11 infusions of 200 mg of iron.²⁹

Zinc

A systematic review of zinc deficiency in patients with IBD identified 7 studies including 2413 patients and revealed those with Crohn disease had a higher prevalence of zinc deficiency compared with patients with ulcerative colitis (54% vs 41%).³⁰

Pathophysiology—Zinc serves as a catalytic cofactor for enzymatic activity within proteins and immune cells.³¹ The homeostasis of zinc is tightly regulated within the brush border of the small intestine by zinc transporters ZIP4 and ZIP1 from the lumen of enterocytes into the bloodstream.³² Inflammation in the small intestine due to Crohn disease can result in zinc malabsorption.

Ranaldi et al³³ exposed intestinal cells and zinc-depleted intestinal cells to tumor necrosis factor α media to simulate an inflammatory environment. They measured transepithelial electrical resistance as a surrogate for transmembrane permeability and found that zinc-depleted cells had a statistically significantly higher transepithelial electrical resistance percentage (60% reduction after 4 hours; P<1.10^–6) when exposed to tumor necrosis factor α signaling compared with normal intestinal cells. They concluded that zinc deficiency can increase intestinal permeability in the presence of inflammation, creating a cycle of further nutrient malabsorption and inflammation exacerbating IBD symptoms.³³

Cutaneous Manifestations—After absorption in the small intestine, approximately 5% of zinc resides in the skin, with the highest concentration in the stratum spinosum.³⁴ A cell study found that keratinocytes in zinc-deficient environments had higher rates of apoptosis compared with cells in normal media. The authors proposed that this higher rate of apoptosis and the resulting inflammation could be a mechanism for developing the desquamative or eczematous scaly plaques that are common cutaneous manifestations of zinc deficiency.³⁵

Other cutaneous findings may include angular cheilitis, stomatitis, glossitis, paronychia, onychodystrophy, generalized alopecia, and delayed wound healing.³⁶ The histopathology of these skin lesions is characterized by granular layer loss, epidermal pallor, confluent parakeratosis, spongiosis, dyskeratosis, and psoriasiform hyperplasia.³⁷

Diagnosis and Monitoring—Assessing serum zinc levels is challenging, as they may decrease during states of inflammation.³⁸ A mouse model study showed a 3.1-fold increase (P<.001) in ZIP14 expression in wild-type mice compared with an IL-6 -/- knock-down model after IL-6 exposure. The authors concluded that the upregulation of ZIP14 in the liver due to inflammatory cytokine upregulation decreases zinc availability in serum.³⁹ Additionally, serum zinc can overestimate the level of deficiency in IBD because approximately 75% of serum zinc is bound to albumin, which decreases in the setting of inflammation.^40-42

Alternatively, alkaline phosphatase (AP), a zinc-dependent metalloenzyme, may be a better evaluator of zinc status during periods of inflammation. A study in rats evaluated zinc through serum zinc levels and AP levels after a period of induced stress to mimic a short-term inflammatory state.⁴³ The researchers found that total body stores of zinc were unaffected throughout the experiment; only serum zinc declined throughout the experiment duration while AP did not. Because approximately 75% of serum zinc is bound to serum albumin,⁴² the researchers concluded the induced inflammatory state depleted serum albumin and redistributed zinc to the liver, causing the observed serum zinc changes, while total body zinc levels and AP were largely unaffected in comparison.⁴³ Comorbid conditions such as liver or bone disease can increase AP levels, which limits the utility of AP as a surrogate for zinc in patients with comorbidities.⁴⁴ However, even in the context of active IBD, serum zinc still is currently considered the best biomarker to evaluate zinc status.⁴⁵

Treatment—The recommended dose for zinc supplementation is 20 to 40 mg daily with higher doses (>50 mg/d) for patients with malabsorptive syndromes such as IBD.⁴⁶ It can be administered orally or parenterally. Although rare, zinc replacement therapy may be associated with diarrhea, nausea, vomiting, mild headaches, and fatigue.⁴⁶ Additional considerations should be taken when repleting other micronutrients with zinc, as calcium and folate can inhibit zinc reabsorption, while zinc itself can inhibit iron and copper reabsorption.⁴⁷

Vitamin D and Calcium

Low vitamin D levels (<50 nmol/L) and hypocalcemia (<8.8 mg/dL) are common in patients with IBD.^48,49

Pathophysiology—Vitamin D levels are maintained via 2 mechanisms. The first mechanism is through the skin, as keratinocytes produce 7-dehydrocholesterol after exposure to UV light, which is converted into previtamin D₃ and then thermally isomerizes into vitamin D₃. This vitamin D₃ is then transported to the liver on vitamin D–binding protein.⁵⁰ The second mechanism is through oral vitamin D₃ that is absorbed through vitamin D receptors in intestinal epithelium and transported to the liver, where it is hydroxylated into 25-hydroxyvitamin D (25[OH]D), then to the kidneys for hydroxylation to 1,25(OH)₂D for redistribution throughout the body.⁵⁰ This activated form of vitamin D regulates calcium absorption in the intestine, and optimal vitamin D levels are necessary to absorb calcium efficiently.⁵¹ Inflammation from IBD within the small intestine can downregulate vitamin D receptors, causing malabsorption and decreased serum vitamin D.⁵²

Vitamin D signaling also is vital to maintaining the tight junctions and adherens junctions of the intestinal epithelium. Weakening the permeability of the epithelium further exacerbates malabsorption and subsequent vitamin D deficiency.⁵² A meta-analysis of 27 studies including 8316 patients with IBD showed low vitamin D levels were associated with increased odds of disease activity (OR=1.53; 95% CI, 1.32-1.77), mucosal inflammation (OR=1.25; 95% CI, 1.06-1.47), and future clinical relapse (OR=1.23; 95% CI, 1.03-1.47) in patients with Crohn disease. The authors concluded that low levels of vitamin D could be used as a potential biomarker of inflammatory status in Crohn disease.⁵³

Vitamin D and calcium are further implicated in maintaining skeletal health,⁴⁷ while vitamin D specifically helps maintain intestinal homeostasis⁵⁴ and immune system modulation in the skin.⁵⁵

Cutaneous Manifestations—Vitamin D is thought to play crucial roles in skin differentiation and proliferation, cutaneous innate immunity, hair follicle cycling, photoprotection, and wound healing.⁵⁶ Vitamin D deficiency has been observed in a large range of cutaneous diseases including skin cancer, psoriasis, vitiligo, bullous pemphigoid, atopic dermatitis, and various types of alopecia.^56-59 It is unclear whether vitamin D deficiency facilitates these disease processes or is merely the consequence of a disrupted cutaneous surface with the inability to complete the first step in vitamin D processing. A 2014 meta-analysis of 290 prospective cohort studies and 172 randomized trials concluded that 25(OH)D deficiency was associated with ill health and did not find causal evidence for any specific disease, dermatologic or otherwise.⁶⁰ Calcium deficiency may cause epidermal changes including dry skin, coarse hair, and brittle nails.⁶¹

Diagnosis and Monitoring—The ECCO guidelines recommend obtaining serum 25(OH)D levels every 3 months in patients with IBD.⁶² Levels less than 75 nmol/L are considered deficient, and a value less than 30 nmol/L increases the risk for osteomalacia and nutritional rickets, constituting severe vitamin D deficiency.^63-65

An observational study of 325 patients with IBD showed a statistically significant negative correlation between serum vitamin D and fecal calprotectin (r=−0.19; P<.001), a stool-based marker for gut inflammation, supporting vitamin D as a potential biomarker in IBD.⁶⁶

Evaluation of calcium can be done through serum levels in patients with IBD.⁶⁷ Patients with IBD are at risk for hypoalbuminemia; therefore, consideration should be taken to ensure calcium levels are corrected, as approximately 50% of calcium is bound to albumin or other ions in the body,⁶⁸ which can be done by adjusting the calcium concentration by 0.02 mmol/L for every 1 g/L of albumin above or below 40 g/L. In the most critically ill patients, a direct ionized calcium blood level should be used instead because the previously mentioned correction calculations are inaccurate when albumin is critically low.⁶⁹

Treatment—The ECCO guidelines recommend calcium and vitamin D repletion of 500 to 1000 mg and 800 to 1000 U, respectively, in patients with IBD on systemic corticosteroids to prevent the negative effects of bone loss.⁶² Calcium repletion in patients with IBD who are not on systemic steroids are the same as for the general population.⁶⁵

Vitamin D repletion also may help decrease IBD activity. In a prospective study, 10,000 IU/d of vitamin D in 10 patients with IBD—adjusted over 12 weeks to a target of 100 to 125 nmol/L of serum 25(OH)D—showed a significant reduction in clinical Crohn activity (P=.019) over the study period.⁷⁰ In contrast, 2000 IU/d for 3 months in an RCT of 27 patients with Crohn disease found significantly lower CRP (P=.019) and significantly higher self-reported quality of life (P=.037) but nonsignificant decreases in Crohn activity (P=.082) in patients with 25(OH)D levels of 75 nmol/L or higher compared with those with 25(OH)D levels less than 75 nmol/L.⁷¹

These discrepancies illustrate the need for expanded clinical trials to elucidate the optimal vitamin D dosing for patients with IBD. Ultimately, assessing vitamin D and calcium status and considering repletion in patients with IBD, especially those with comorbid dermatologic diseases such as poor wound healing, psoriasis, or atopic dermatitis, is important.

Vitamin B₆ (Pyridoxine)

Pathophysiology—Pyridoxine is an important coenzyme for many functions including amino acid transamination, fatty acid metabolism, and conversion of tryptophan to niacin. It is absorbed in the jejunum and ileum and subsequently transported to the liver for rephosphorylation and release into its active form.³⁶ An observational study assessing the nutritional status of patients with IBD found that only 5.7% of 105 patients with food records had inadequate dietary intake of pyridoxine, but 29% of all patients with IBD had subnormal pyridoxine levels.⁷² Additionally, they found no significant difference in the prevalence of subnormal pyridoxine levels in patients with active IBD vs IBD in remission. The authors suggested that the subnormal pyridoxine levels in patients with IBD likely were multifactorial and resulted from malabsorption due to active disease, inflammation, and inadequate intake.⁷²

Cutaneous Manifestations—Cutaneous findings associated with pyridoxine deficiency include periorificial and perineal dermatitis,⁷³ angular stomatitis, and cheilitis with associated burning, redness, and tongue edema.³⁶ Additionally, pyridoxine is involved in the conversion of tryptophan to niacin, and its deficiency may manifest with pellagralike findings.⁷⁴

Because pyridoxine is critical to protein metabolism, its deficiency may disrupt key cellular structures that rely on protein concentrations to maintain structural integrity. One such structure in the skin that heavily relies on protein concentrations is the ground substance of the extracellular matrix—the amorphous gelatinous spaces that occupy the areas between the extracellular matrix, which consists of cross-linked glycosaminoglycans and proteins.⁷⁵ Without protein, ground substance increases in viscosity and can disrupt the epidermal barrier, leading to increased transepidermal water loss and ultimately inflammation.⁷⁶ Although this theory has yet to be validated fully, this is a potential mechanistic explanation for the inflammation in dermal papillae that leads to dermatitis observed in pyridoxine deficiency.

Diagnosis and Monitoring—Direct biomarkers of pyridoxine status are in serum, plasma, erythrocytes, and urine, with the most common measurement in plasma as pyridoxal 5′-phosphate (PLP).⁷⁷ Plasma PLP concentrations lower than 20 nmol/L are suggestive of deficiency.⁷⁸ Plasma PLP has shown inverse relationships with acute phase inflammatory markers CRP⁷⁹ and AP,⁷⁸ thereby raising concerns for its validity to assess pyridoxine status in patients with symptomatic IBD.⁸⁰

Alternative evaluations of pyridoxine include tryptophan and methionine loading tests,³⁶ which are measured via urinary excretion and require normal kidney function to be accurate. They should be considered in IBD if necessary, but routine testing, even in patients with symptomatic IBD, is not recommended in the ECCO guidelines. Additional considerations should be taken in patients with altered nutrient requirements such as those who have undergone bowel resection due to highly active disease or those who receive parenteral nutritional supplementation.⁸¹

Treatment—Recommendations for oral pyridoxine supplementation range from 25 to 600 mg daily,⁸² with symptoms typically improving on 100 mg daily.³⁶ Pyridoxine supplementation may have additional benefits for patients with IBD and potentially modulate disease severity. An IL-10 knockout mouse supplemented with pyridoxine had an approximately 60% reduction (P<.05) in inflammation compared to mice deficient in pyridoxine.⁸³ The authors suggest that PLP-dependent enzymes can inhibit further proinflammatory signaling and T-cell migration that can exacerbate IBD. Ultimately, more data is needed before determining the efficacy of pyridoxine supplementation for active IBD.

Vitamin B₁₂ and Vitamin B₉ (Folic Acid)

Pathophysiology—Vitamin B₁₂ is reabsorbed in the terminal ileum, the distal portion of the small intestine. The American Gastroenterological Association recommends that patients with a history of extensive ileal disease or prior ileal surgery, which is the case for many patients with Crohn disease, be monitored for vitamin B₁₂ deficiency.²³ Monitoring and rapid supplementation of vitamin B₁₂ can prevent pernicious anemia and irreversible neurologic damage that may result from deficiency.⁸⁴

Folic acid is primarily absorbed in the duodenum and jejunum of the small intestine. A meta-analysis performed in 2017 assessed studies observing folic acid and vitamin B₁₂ levels in 1086 patients with IBD compared with 1484 healthy controls and found an average difference in serum folate concentration of 0.46 nmol/L (P<.001).⁸⁴ Interestingly, this study did not find a significant difference in serum vitamin B₁₂ levels between patients with IBD and healthy controls, highlighting the mechanism of vitamin B₁₂ deficiency in IBD because only patients with terminal ileal involvement are at risk for malabsorption and subsequent deficiency.

Cutaneous Manifestations—Both vitamin B₁₂ and folic acid deficiency can manifest as cheilitis, glossitis, and/or generalized hyperpigmentation that is accentuated in the flexural areas, palms, soles, and oral cavity.^85,86 Systemic symptoms of patients with vitamin B₁₂ and folic acid deficiency include megaloblastic anemia, pallor, and fatigue. A potential mechanism for the hyperpigmentation observed from vitamin B₁₂ deficiency came from an electron microscope study that showed an increased concentration of melanosomes in a patient with deficiency.⁸⁷

Diagnosis and Monitoring—In patients with suspected vitamin B₁₂ and/or folic acid deficiency, initial evaluation should include a CBC with peripheral smear and serum vitamin B₁₂ and folate levels. In cases for which the diagnosis still is unclear after initial testing, methylmalonic acid and homocysteine levels can help differentiate between the 2 deficiencies. Methylmalonic acid classically is elevated (>260 nmol/L) in vitamin B₁₂ deficiency but not in folate deficiency.⁸⁸ Cut-off values for vitamin B₁₂ deficiency are less than 200 to 250 pg/mL forserum vitamin B₁₂ and/or an elevated level of methylmalonic acid (>0.271 µmol/L).⁸⁹ A serum folic acid value greater than 3 ng/mL and/or erythrocyte folate concentrations greater than 140 ng/mL are considered adequate, whereas an indicator of folic acid deficiency is a homocysteine level less than 10 µmol/L.⁹⁰ A CBC can screen for macrocytic megaloblastic anemias (mean corpuscular volume >100 fl), which are classic diagnostic signs of an underlying vitamin B₁₂ or folate deficiency.

Treatment—According to the Centers for Disease Control and Prevention, supplementation of vitamin B₁₂ can be done orally with 1000 µg daily in patients with deficiency. In patients with active IBD, oral reabsorption of vitamin B₁₂ can be less effective, making subcutaneous or intramuscular administration (1000 µg/wk for 8 weeks, then monthly for life) better options.⁸⁹

Patients with IBD managed with methotrexate should be screened carefully for folate deficiency. Methotrexate is a folate analog that sometimes is used for the treatment of IBD. Reversible competitive inhibition of dihydrofolate reductase can precipitate a systemic folic acid decrease.⁹¹ Typically, oral folic acid (1 to 5 mg/d) is sufficient to treat folate deficiency, with the ESPEN recommending 5 mg once weekly 24 to 72 hours after methotrexate treatment or 1 mg daily for 5 days per week in patients with IBD.¹ Alternative formulations—IV, subcutaneous, or intramuscular—are available for patients who cannot tolerate oral intake.⁹²

Final Thoughts

Dermatologists can be the first to observe the cutaneous manifestations of micronutrient deficiencies. Although the symptoms of each micronutrient deficiency discussed may overlap, attention to small clinical clues in patients with IBD can improve patient outcomes and quality of life. For example, koilonychia with glossitis and xerosis likely is due to iron deficiency, while zinc deficiency should be suspected in patients with scaly eczematous plaques in skin folds. A high level of suspicion for micronutrient deficiencies in patients with IBD should be followed by a complete patient history, review of systems, and thorough clinical examination. A thorough laboratory evaluation can pinpoint nutritional deficiencies in patients with IBD, keeping in mind that specific biomarkers such as ferritin and serum zinc also act as acute phase reactants and should be interpreted in this context. Co-management with gastroenterologists should be a priority in patients with IBD, as gaining control of inflammatory disease is crucial for the prevention of recurrent vitamin and micronutrient deficiencies in addition to long-term health in this population.

In 2023, ESPEN (the European Society for Clinical Nutrition and Metabolism) published consensus recommendations highlighting the importance of regular monitoring and treatment of nutrient deficiencies in patients with inflammatory bowel disease (IBD) for improved prognosis, mortality, and quality of life.¹ Suboptimal nutrition in patients with IBD predominantly results from inflammation of the gastrointestinal (GI) tract leading to malabsorption; however, medications commonly used to manage IBD also can contribute to malnutrition.^2,3 Additionally, patients may develop nausea and food avoidance due to medication or the disease itself, leading to nutritional withdrawal and eventual deficiency.⁴ Even with the development of diets focused on balancing nutritional needs and decreasing inflammation,⁵ offsetting this aversion to food can be difficult to overcome.²

Cutaneous manifestations of IBD are multifaceted and can be secondary to the disease, reactive to or associated with IBD, or effects from nutritional deficiencies. The most common vitamin and nutrient deficiencies in patients with IBD include iron; zinc; calcium; vitamin D; and vitamins B₆ (pyridoxine), B₉ (folic acid), and B₁₂.⁶ Malnutrition may manifest with cutaneous disease, and dermatologists can be the first to identify and assess for nutritional deficiencies. In this article, we review the mechanisms of these micronutrient depletions in the context of IBD, their subsequent dermatologic manifestations (Table), and treatment and monitoring guidelines for each deficiency.

Iron

A systematic review conducted from 2007 to 2012 in European patients with IBD (N=2192) found the overall prevalence of anemia in this population to be 24% (95% CI, 18%-31%), with 57% of patients with anemia experiencing iron deficiency.⁷ Anemia is observed more commonly in patients hospitalized with IBD and is common in patients with both Crohn disease and ulcerative colitis.⁸

Pathophysiology—Iron is critically important in oxygen transportation throughout the body as a major component of hemoglobin. Physiologically, the low pH of the duodenum and proximal jejunum allows divalent metal transporter 1 to transfer dietary Fe³⁺ into enterocytes, where it is reduced to the transportable Fe²⁺.^9,10 Distribution of Fe²⁺ ions from enterocytes relies on ferroportin, an iron-transporting protein, which is heavily regulated by the protein hepcidin.¹¹ Hepcidin, a known acute phase reactant, will increase in the setting of active IBD, causing a depletion of ferroportin and an inability of the body to utilize the stored iron in enterocytes.¹² This poor utilization of iron stores combined with blood loss caused by inflammation in the GI tract is the proposed primary mechanism of iron-deficiency anemia observed in patients with IBD.¹³

Cutaneous Manifestations—From a dermatologic perspective, iron-deficiency anemia can manifest with a wide range of symptoms including glossitis, koilonychia, xerosis and/or pruritus, and brittle hair or hair loss.^14,15 Although the underlying pathophysiology of these cutaneous manifestations is not fully understood, there are several theories assessing the mechanisms behind the skin findings of iron deficiency.

Atrophic glossitis has been observed in many patients with iron deficiency and is thought to manifest due to low iron concentrations in the blood, thereby decreasing oxygen delivery to the papillae of the dorsal tongue with resultant atrophy.^16,17 Similarly, decreased oxygen delivery to the nail bed capillaries may cause deformities in the nail called koilonychia (or “spoon nails”).¹⁸ Iron is a key co-factor in collagen lysyl hydroxylase that promotes collagen binding; iron deficiency may lead to disruptions in the epidermal barrier that can cause pruritus and xerosis.¹⁹ An observational study of 200 healthy patients with a primary concern of pruritus found a correlation between low serum ferritin and a higher degree of pruritus (r=−0.768; P<.00001).²⁰

Evidence for iron’s role in hair growth comes from a mouse model study with a mutation in the serine protease TMPRSS6—a protein that regulates hepcidin and iron absorption—which caused an increase in hepcidin production and subsequent systemic iron deficiency. Mice at 4 weeks of age were devoid of all body hair but had substantial regrowth after initiation of a 2-week iron-rich diet, which suggests a connection between iron repletion and hair growth in mice with iron deficiency.²¹ Additionally, a meta-analysis analyzing the comorbidities of patients with alopecia areata found them to have higher odds (odds ratio [OR]=2.78; 95% CI, 1.23-6.29) of iron-deficiency anemia but no association with IBD (OR=1.48; 95% CI, 0.32-6.82).²²

Diagnosis and Monitoring—The American Gastroenterological Association recommends a complete blood cell count (CBC), serum ferritin, transferrin saturation (TfS), and C-reactive protein (CRP) as standard evaluations for iron deficiency in patients with IBD. Patients with active IBD should be screened every 3 months,and patients with inactive disease should be screened every 6 to 12 months.²³

Although ferritin and TfS often are used as markers for iron status in healthy individuals, they are positive and negative acute phase reactants, respectively. Using them to assess iron status in patients with IBD may inaccurately represent iron status in the setting of inflammation from the disease.²⁴ The European Crohn’s and Colitis Organisation (ECCO) produced guidelines to define iron deficiency as a TfS less than 20% or a ferritin level less than 30 µg/L in patients without evidence of active IBD and a ferritin level less than 100 µg/L for patients with active inflammation.²⁵

A 2020 multicenter observational study of 202 patients with diagnosed IBD found that the ECCO guideline of ferritin less than 30 µg/L had an area under the receiver operating characteristic (AUROC) curve of 0.69, a sensitivity of 0.43, and a specificity of 0.95 in their population.²⁶ In a sensitivity analysis stratifying patients by CRP level (<10 or ≥10 mg/L), the authors found that for patients with ulcerative colitis and a CRP less than 10 mg/L, a cut-off value of ferritin less than 65 µg/L (AUROC=0.78) had a sensitivity of 0.78 and specificity of 0.76, and a TfS value of less than 16% (AUROC=0.88) had a sensitivity of 0.79 and a specificity of 0.9. In patients with a CRP of 10 mg/L or greater, a cut-off value of ferritin 80 µg/L (AUROC=0.76) had a sensitivity of 0.75 and a specificity of 0.82, and a TfS value of less than 11% (AUROC=0.69) had a sensitivity of 0.79 and a specificity of 0.88. There were no ferritin cut-off values associated with good diagnostic performance (defined as both sensitivity and specificity >0.70) for iron deficiency in patients with Crohn disease.²⁶

The authors recommended using an alternative iron measurement such as soluble transferrin receptor (sTfR)/log ferritin ratio (TfR-F) that is not influenced by active inflammation and has a good correlation with ferritin values (TfR-F: r=0.66; P<.001).²⁶ However, both sTfR and TfR-F have high costs and intermethod variability as well as differences in their reference ranges depending on which laboratory performs the analysis, limiting the accessibility and practicality of easily obtaining these tests.²⁷ Although there may be inaccuracies for standard ferritin or TfS under ECCO guidelines, proposed alternatives have their own limitations, which may make ferritin and TfS the most reasonable evaluations of iron status as long as disease activity status at the time of testing is taken into consideration.

Treatment—Treatment of underlying iron deficiency in patients with IBD requires reversing the cause of the deficiency and supplementing iron. In patients with IBD, the options to supplement iron may be limited by active disease, making oral intake less effective. Oral iron supplementation also is associated with notable GI adverse effects that may be exacerbated in patients with IBD. A systematic review of 43 randomized controlled trials (RCTs) evaluating GI adverse effects (eg, nausea, abdominal pain, diarrhea, constipation, and black or tarry stools) of oral ferrous sulfate compared with placebo or intravenous (IV) iron supplementation in healthy nonanemic individuals found a significant increase in GI adverse effects with oral supplementation (placebo: OR=2.32; P<.0001; IV: OR=3.05; P<.0001).²⁸

Therefore, IV iron repletion may be necessary in patients with IBD and may require numerous infusions depending on the formulation of iron. In an RCT conducted in 2011, patients with iron-deficiency anemia with quiescent or mild to moderate IBD were treated with either IV iron sulfate or ferric carboxymaltose.²⁹ With a primary end point of hemoglobin response greater than 2 g/dL, the authors found that 150 of 240 patients responded to ferric carboxymaltose vs 118 of 235 treated with iron sulfate (P=.004). The dosing for ferric carboxymaltose was 1 to 3 infusions of 500 to 1000 mg of iron and for iron sulfate up to 11 infusions of 200 mg of iron.²⁹

Zinc

A systematic review of zinc deficiency in patients with IBD identified 7 studies including 2413 patients and revealed those with Crohn disease had a higher prevalence of zinc deficiency compared with patients with ulcerative colitis (54% vs 41%).³⁰

Pathophysiology—Zinc serves as a catalytic cofactor for enzymatic activity within proteins and immune cells.³¹ The homeostasis of zinc is tightly regulated within the brush border of the small intestine by zinc transporters ZIP4 and ZIP1 from the lumen of enterocytes into the bloodstream.³² Inflammation in the small intestine due to Crohn disease can result in zinc malabsorption.

Ranaldi et al³³ exposed intestinal cells and zinc-depleted intestinal cells to tumor necrosis factor α media to simulate an inflammatory environment. They measured transepithelial electrical resistance as a surrogate for transmembrane permeability and found that zinc-depleted cells had a statistically significantly higher transepithelial electrical resistance percentage (60% reduction after 4 hours; P<1.10^–6) when exposed to tumor necrosis factor α signaling compared with normal intestinal cells. They concluded that zinc deficiency can increase intestinal permeability in the presence of inflammation, creating a cycle of further nutrient malabsorption and inflammation exacerbating IBD symptoms.³³

Cutaneous Manifestations—After absorption in the small intestine, approximately 5% of zinc resides in the skin, with the highest concentration in the stratum spinosum.³⁴ A cell study found that keratinocytes in zinc-deficient environments had higher rates of apoptosis compared with cells in normal media. The authors proposed that this higher rate of apoptosis and the resulting inflammation could be a mechanism for developing the desquamative or eczematous scaly plaques that are common cutaneous manifestations of zinc deficiency.³⁵

Other cutaneous findings may include angular cheilitis, stomatitis, glossitis, paronychia, onychodystrophy, generalized alopecia, and delayed wound healing.³⁶ The histopathology of these skin lesions is characterized by granular layer loss, epidermal pallor, confluent parakeratosis, spongiosis, dyskeratosis, and psoriasiform hyperplasia.³⁷

Diagnosis and Monitoring—Assessing serum zinc levels is challenging, as they may decrease during states of inflammation.³⁸ A mouse model study showed a 3.1-fold increase (P<.001) in ZIP14 expression in wild-type mice compared with an IL-6 -/- knock-down model after IL-6 exposure. The authors concluded that the upregulation of ZIP14 in the liver due to inflammatory cytokine upregulation decreases zinc availability in serum.³⁹ Additionally, serum zinc can overestimate the level of deficiency in IBD because approximately 75% of serum zinc is bound to albumin, which decreases in the setting of inflammation.^40-42

Alternatively, alkaline phosphatase (AP), a zinc-dependent metalloenzyme, may be a better evaluator of zinc status during periods of inflammation. A study in rats evaluated zinc through serum zinc levels and AP levels after a period of induced stress to mimic a short-term inflammatory state.⁴³ The researchers found that total body stores of zinc were unaffected throughout the experiment; only serum zinc declined throughout the experiment duration while AP did not. Because approximately 75% of serum zinc is bound to serum albumin,⁴² the researchers concluded the induced inflammatory state depleted serum albumin and redistributed zinc to the liver, causing the observed serum zinc changes, while total body zinc levels and AP were largely unaffected in comparison.⁴³ Comorbid conditions such as liver or bone disease can increase AP levels, which limits the utility of AP as a surrogate for zinc in patients with comorbidities.⁴⁴ However, even in the context of active IBD, serum zinc still is currently considered the best biomarker to evaluate zinc status.⁴⁵

Treatment—The recommended dose for zinc supplementation is 20 to 40 mg daily with higher doses (>50 mg/d) for patients with malabsorptive syndromes such as IBD.⁴⁶ It can be administered orally or parenterally. Although rare, zinc replacement therapy may be associated with diarrhea, nausea, vomiting, mild headaches, and fatigue.⁴⁶ Additional considerations should be taken when repleting other micronutrients with zinc, as calcium and folate can inhibit zinc reabsorption, while zinc itself can inhibit iron and copper reabsorption.⁴⁷

Vitamin D and Calcium

Low vitamin D levels (<50 nmol/L) and hypocalcemia (<8.8 mg/dL) are common in patients with IBD.^48,49

Pathophysiology—Vitamin D levels are maintained via 2 mechanisms. The first mechanism is through the skin, as keratinocytes produce 7-dehydrocholesterol after exposure to UV light, which is converted into previtamin D₃ and then thermally isomerizes into vitamin D₃. This vitamin D₃ is then transported to the liver on vitamin D–binding protein.⁵⁰ The second mechanism is through oral vitamin D₃ that is absorbed through vitamin D receptors in intestinal epithelium and transported to the liver, where it is hydroxylated into 25-hydroxyvitamin D (25[OH]D), then to the kidneys for hydroxylation to 1,25(OH)₂D for redistribution throughout the body.⁵⁰ This activated form of vitamin D regulates calcium absorption in the intestine, and optimal vitamin D levels are necessary to absorb calcium efficiently.⁵¹ Inflammation from IBD within the small intestine can downregulate vitamin D receptors, causing malabsorption and decreased serum vitamin D.⁵²

Vitamin D signaling also is vital to maintaining the tight junctions and adherens junctions of the intestinal epithelium. Weakening the permeability of the epithelium further exacerbates malabsorption and subsequent vitamin D deficiency.⁵² A meta-analysis of 27 studies including 8316 patients with IBD showed low vitamin D levels were associated with increased odds of disease activity (OR=1.53; 95% CI, 1.32-1.77), mucosal inflammation (OR=1.25; 95% CI, 1.06-1.47), and future clinical relapse (OR=1.23; 95% CI, 1.03-1.47) in patients with Crohn disease. The authors concluded that low levels of vitamin D could be used as a potential biomarker of inflammatory status in Crohn disease.⁵³

Vitamin D and calcium are further implicated in maintaining skeletal health,⁴⁷ while vitamin D specifically helps maintain intestinal homeostasis⁵⁴ and immune system modulation in the skin.⁵⁵

Cutaneous Manifestations—Vitamin D is thought to play crucial roles in skin differentiation and proliferation, cutaneous innate immunity, hair follicle cycling, photoprotection, and wound healing.⁵⁶ Vitamin D deficiency has been observed in a large range of cutaneous diseases including skin cancer, psoriasis, vitiligo, bullous pemphigoid, atopic dermatitis, and various types of alopecia.^56-59 It is unclear whether vitamin D deficiency facilitates these disease processes or is merely the consequence of a disrupted cutaneous surface with the inability to complete the first step in vitamin D processing. A 2014 meta-analysis of 290 prospective cohort studies and 172 randomized trials concluded that 25(OH)D deficiency was associated with ill health and did not find causal evidence for any specific disease, dermatologic or otherwise.⁶⁰ Calcium deficiency may cause epidermal changes including dry skin, coarse hair, and brittle nails.⁶¹

Diagnosis and Monitoring—The ECCO guidelines recommend obtaining serum 25(OH)D levels every 3 months in patients with IBD.⁶² Levels less than 75 nmol/L are considered deficient, and a value less than 30 nmol/L increases the risk for osteomalacia and nutritional rickets, constituting severe vitamin D deficiency.^63-65

An observational study of 325 patients with IBD showed a statistically significant negative correlation between serum vitamin D and fecal calprotectin (r=−0.19; P<.001), a stool-based marker for gut inflammation, supporting vitamin D as a potential biomarker in IBD.⁶⁶

Evaluation of calcium can be done through serum levels in patients with IBD.⁶⁷ Patients with IBD are at risk for hypoalbuminemia; therefore, consideration should be taken to ensure calcium levels are corrected, as approximately 50% of calcium is bound to albumin or other ions in the body,⁶⁸ which can be done by adjusting the calcium concentration by 0.02 mmol/L for every 1 g/L of albumin above or below 40 g/L. In the most critically ill patients, a direct ionized calcium blood level should be used instead because the previously mentioned correction calculations are inaccurate when albumin is critically low.⁶⁹

Treatment—The ECCO guidelines recommend calcium and vitamin D repletion of 500 to 1000 mg and 800 to 1000 U, respectively, in patients with IBD on systemic corticosteroids to prevent the negative effects of bone loss.⁶² Calcium repletion in patients with IBD who are not on systemic steroids are the same as for the general population.⁶⁵

Vitamin D repletion also may help decrease IBD activity. In a prospective study, 10,000 IU/d of vitamin D in 10 patients with IBD—adjusted over 12 weeks to a target of 100 to 125 nmol/L of serum 25(OH)D—showed a significant reduction in clinical Crohn activity (P=.019) over the study period.⁷⁰ In contrast, 2000 IU/d for 3 months in an RCT of 27 patients with Crohn disease found significantly lower CRP (P=.019) and significantly higher self-reported quality of life (P=.037) but nonsignificant decreases in Crohn activity (P=.082) in patients with 25(OH)D levels of 75 nmol/L or higher compared with those with 25(OH)D levels less than 75 nmol/L.⁷¹

These discrepancies illustrate the need for expanded clinical trials to elucidate the optimal vitamin D dosing for patients with IBD. Ultimately, assessing vitamin D and calcium status and considering repletion in patients with IBD, especially those with comorbid dermatologic diseases such as poor wound healing, psoriasis, or atopic dermatitis, is important.

Vitamin B₆ (Pyridoxine)

Pathophysiology—Pyridoxine is an important coenzyme for many functions including amino acid transamination, fatty acid metabolism, and conversion of tryptophan to niacin. It is absorbed in the jejunum and ileum and subsequently transported to the liver for rephosphorylation and release into its active form.³⁶ An observational study assessing the nutritional status of patients with IBD found that only 5.7% of 105 patients with food records had inadequate dietary intake of pyridoxine, but 29% of all patients with IBD had subnormal pyridoxine levels.⁷² Additionally, they found no significant difference in the prevalence of subnormal pyridoxine levels in patients with active IBD vs IBD in remission. The authors suggested that the subnormal pyridoxine levels in patients with IBD likely were multifactorial and resulted from malabsorption due to active disease, inflammation, and inadequate intake.⁷²

Cutaneous Manifestations—Cutaneous findings associated with pyridoxine deficiency include periorificial and perineal dermatitis,⁷³ angular stomatitis, and cheilitis with associated burning, redness, and tongue edema.³⁶ Additionally, pyridoxine is involved in the conversion of tryptophan to niacin, and its deficiency may manifest with pellagralike findings.⁷⁴

Because pyridoxine is critical to protein metabolism, its deficiency may disrupt key cellular structures that rely on protein concentrations to maintain structural integrity. One such structure in the skin that heavily relies on protein concentrations is the ground substance of the extracellular matrix—the amorphous gelatinous spaces that occupy the areas between the extracellular matrix, which consists of cross-linked glycosaminoglycans and proteins.⁷⁵ Without protein, ground substance increases in viscosity and can disrupt the epidermal barrier, leading to increased transepidermal water loss and ultimately inflammation.⁷⁶ Although this theory has yet to be validated fully, this is a potential mechanistic explanation for the inflammation in dermal papillae that leads to dermatitis observed in pyridoxine deficiency.

Diagnosis and Monitoring—Direct biomarkers of pyridoxine status are in serum, plasma, erythrocytes, and urine, with the most common measurement in plasma as pyridoxal 5′-phosphate (PLP).⁷⁷ Plasma PLP concentrations lower than 20 nmol/L are suggestive of deficiency.⁷⁸ Plasma PLP has shown inverse relationships with acute phase inflammatory markers CRP⁷⁹ and AP,⁷⁸ thereby raising concerns for its validity to assess pyridoxine status in patients with symptomatic IBD.⁸⁰

Alternative evaluations of pyridoxine include tryptophan and methionine loading tests,³⁶ which are measured via urinary excretion and require normal kidney function to be accurate. They should be considered in IBD if necessary, but routine testing, even in patients with symptomatic IBD, is not recommended in the ECCO guidelines. Additional considerations should be taken in patients with altered nutrient requirements such as those who have undergone bowel resection due to highly active disease or those who receive parenteral nutritional supplementation.⁸¹

Treatment—Recommendations for oral pyridoxine supplementation range from 25 to 600 mg daily,⁸² with symptoms typically improving on 100 mg daily.³⁶ Pyridoxine supplementation may have additional benefits for patients with IBD and potentially modulate disease severity. An IL-10 knockout mouse supplemented with pyridoxine had an approximately 60% reduction (P<.05) in inflammation compared to mice deficient in pyridoxine.⁸³ The authors suggest that PLP-dependent enzymes can inhibit further proinflammatory signaling and T-cell migration that can exacerbate IBD. Ultimately, more data is needed before determining the efficacy of pyridoxine supplementation for active IBD.

Vitamin B₁₂ and Vitamin B₉ (Folic Acid)

Pathophysiology—Vitamin B₁₂ is reabsorbed in the terminal ileum, the distal portion of the small intestine. The American Gastroenterological Association recommends that patients with a history of extensive ileal disease or prior ileal surgery, which is the case for many patients with Crohn disease, be monitored for vitamin B₁₂ deficiency.²³ Monitoring and rapid supplementation of vitamin B₁₂ can prevent pernicious anemia and irreversible neurologic damage that may result from deficiency.⁸⁴

Folic acid is primarily absorbed in the duodenum and jejunum of the small intestine. A meta-analysis performed in 2017 assessed studies observing folic acid and vitamin B₁₂ levels in 1086 patients with IBD compared with 1484 healthy controls and found an average difference in serum folate concentration of 0.46 nmol/L (P<.001).⁸⁴ Interestingly, this study did not find a significant difference in serum vitamin B₁₂ levels between patients with IBD and healthy controls, highlighting the mechanism of vitamin B₁₂ deficiency in IBD because only patients with terminal ileal involvement are at risk for malabsorption and subsequent deficiency.

Cutaneous Manifestations—Both vitamin B₁₂ and folic acid deficiency can manifest as cheilitis, glossitis, and/or generalized hyperpigmentation that is accentuated in the flexural areas, palms, soles, and oral cavity.^85,86 Systemic symptoms of patients with vitamin B₁₂ and folic acid deficiency include megaloblastic anemia, pallor, and fatigue. A potential mechanism for the hyperpigmentation observed from vitamin B₁₂ deficiency came from an electron microscope study that showed an increased concentration of melanosomes in a patient with deficiency.⁸⁷

Diagnosis and Monitoring—In patients with suspected vitamin B₁₂ and/or folic acid deficiency, initial evaluation should include a CBC with peripheral smear and serum vitamin B₁₂ and folate levels. In cases for which the diagnosis still is unclear after initial testing, methylmalonic acid and homocysteine levels can help differentiate between the 2 deficiencies. Methylmalonic acid classically is elevated (>260 nmol/L) in vitamin B₁₂ deficiency but not in folate deficiency.⁸⁸ Cut-off values for vitamin B₁₂ deficiency are less than 200 to 250 pg/mL forserum vitamin B₁₂ and/or an elevated level of methylmalonic acid (>0.271 µmol/L).⁸⁹ A serum folic acid value greater than 3 ng/mL and/or erythrocyte folate concentrations greater than 140 ng/mL are considered adequate, whereas an indicator of folic acid deficiency is a homocysteine level less than 10 µmol/L.⁹⁰ A CBC can screen for macrocytic megaloblastic anemias (mean corpuscular volume >100 fl), which are classic diagnostic signs of an underlying vitamin B₁₂ or folate deficiency.

Treatment—According to the Centers for Disease Control and Prevention, supplementation of vitamin B₁₂ can be done orally with 1000 µg daily in patients with deficiency. In patients with active IBD, oral reabsorption of vitamin B₁₂ can be less effective, making subcutaneous or intramuscular administration (1000 µg/wk for 8 weeks, then monthly for life) better options.⁸⁹

Patients with IBD managed with methotrexate should be screened carefully for folate deficiency. Methotrexate is a folate analog that sometimes is used for the treatment of IBD. Reversible competitive inhibition of dihydrofolate reductase can precipitate a systemic folic acid decrease.⁹¹ Typically, oral folic acid (1 to 5 mg/d) is sufficient to treat folate deficiency, with the ESPEN recommending 5 mg once weekly 24 to 72 hours after methotrexate treatment or 1 mg daily for 5 days per week in patients with IBD.¹ Alternative formulations—IV, subcutaneous, or intramuscular—are available for patients who cannot tolerate oral intake.⁹²

Final Thoughts

Dermatologists can be the first to observe the cutaneous manifestations of micronutrient deficiencies. Although the symptoms of each micronutrient deficiency discussed may overlap, attention to small clinical clues in patients with IBD can improve patient outcomes and quality of life. For example, koilonychia with glossitis and xerosis likely is due to iron deficiency, while zinc deficiency should be suspected in patients with scaly eczematous plaques in skin folds. A high level of suspicion for micronutrient deficiencies in patients with IBD should be followed by a complete patient history, review of systems, and thorough clinical examination. A thorough laboratory evaluation can pinpoint nutritional deficiencies in patients with IBD, keeping in mind that specific biomarkers such as ferritin and serum zinc also act as acute phase reactants and should be interpreted in this context. Co-management with gastroenterologists should be a priority in patients with IBD, as gaining control of inflammatory disease is crucial for the prevention of recurrent vitamin and micronutrient deficiencies in addition to long-term health in this population.

To the Editor:

Eosinophilic pustular folliculitis (EPF) is a noninfectious dermatosis that typically manifests as recurrent follicular papulopustules that generally affect the face and occasionally the trunk and arms. There are several subtypes of EPF: classic EPF (Ofuji disease), infancy-associated EPF, and immunosuppression-associated EPF.^1,2 We report a rare case of EPF in the setting of untreated chronic lymphocytic leukemia (CLL), a subtype of immunosuppression­-associated EPF that has been associated with hematologic malignancy EPF (HM-EPF).^3-5

A 69-year-old woman presented with diffusely scattered, pruritic, erythematous, erosive lesions on the back, arms, legs, and forehead (Figure 1) of 4 months’ duration, as well as an ulcerative lesion on the left third toe due to a suspected insect bite. She had a history of untreated CLL that was diagnosed 2 years prior. The patient was empirically started on clindamycin for presumed infection of the toe. A punch biopsy of the left wrist revealed superficial and deep dermal perivascular and interstitial inflammatory infiltrates composed of lymphocytes, histiocytes, and numerous eosinophils in association with edema and necrosis. Histopathology was overall most consistent with an exuberant arthropod reaction; however, at 2-week follow-up, the patient reported that the pustular lesions improved upon starting antibiotics, which raised concerns for a bacterial process. The patient initially was continued on clindamycin given subjective improvement but was later switched to daptomycin, as she developed clindamycin-resistant methicillin-resistant Staphylococcus aureus osteomyelitis from the necrotic toe.

A month later, the patient returned with new papules and pustules on the arms and trunk. A repeat biopsy showed notable dermal collections comprised predominantly of neutrophils and eosinophils as well as involvement of follicular structures by dense inflammation (Figure 2). Immunohistochemistry demonstrated a predominant population of small CD3⁺ T cells, which raised concern for cutaneous T-cell lymphoma. However, retention of CD5 expression made this less likely. Few scattered CD20⁺ B cells with limited CD23 reactivity and without CD5 co-expression were detected, which ruled out cutaneous involvement of the patient’s CLL. Bacterial culture and Grocott methenamine-silver, Gram, acid-fast bacilli, and periodic acid-Schiff stains were negative. Polymerase chain reaction testing for varicella-zoster virus and herpes simplex virus also were negative. Thus, a diagnosis of EPF secondary to CLL was favored, as an infectious process also was unlikely. The patient was started on triamcinolone cream 0.1% with gradual improvement.

Cases of HM-EPF predominantly have been reported in patients who have undergone chemotherapy, bone marrow transplantation, or hematopoietic stem cell transplantation. Furthermore, a vast majority of these cases have been reported in older males.^3-16 In a retrospective study of more than 750 patients with established CLL, Agnew et al⁷ identified 125 different skin complications in 40 patients. Of this subset, only a small number (2/40) were associated with eosinophilic folliculitis, with 1 case noted in a middle-aged woman with a history of CLL treatment.⁷ Moreover, Motaparthi et al⁴ reported 3 additional cases of HM-EPF, with all patients identified as middle-aged men who were treated with chemotherapy for underlying CLL. Our patient represents a case of EPF in the context of untreated CLL in a woman.

Although topical corticosteroids remain the first-line treatment for EPF, a survey study conducted across 67 hospitals in Japan indicated that antibiotics were moderately or highly effective in 79% of EPF patients (n=143).¹⁷ This association may explain the subjective improvement reported by our patient upon starting clindamycin. Furthermore, in HIV-associated EPF, high-dose cetirizine, itraconazole, and metronidazole have been successful when topical therapies have failed.¹⁸ Although the precise pathogenesis of EPF is unknown, histopathologic features, clinical appearance, and identification of the accurate EPF subtype can still prove valuable in informing empiric treatment strategies. Consequently, the initial histopathologic diagnosis of an arthropod bite reaction in our patient highlights the importance of clinical correlation and additional ancillary studies in the determination of EPF vs other inflammatory dermatoses that manifest microscopically with lymphocytic infiltrates, prominent eosinophils, and follicular involvement.⁴ The histopathologic features of EPF demonstrate considerable overlap with eosinophilic dermatosis of hematologic malignancy (also known as eosinophilic dermatosis of myeloproliferative disease). It is suspected that eosinophilic dermatosis of hematologic malignancy and EPF may exist on a spectrum, and additional cases may improve categorization of these entities.¹⁹

In conclusion, this report adds to the medical practitioner’s awareness of EPF manifestations in patients with underlying CLL, an infrequently reported subtype of HM-EPF.

To the Editor:

Eosinophilic pustular folliculitis (EPF) is a noninfectious dermatosis that typically manifests as recurrent follicular papulopustules that generally affect the face and occasionally the trunk and arms. There are several subtypes of EPF: classic EPF (Ofuji disease), infancy-associated EPF, and immunosuppression-associated EPF.^1,2 We report a rare case of EPF in the setting of untreated chronic lymphocytic leukemia (CLL), a subtype of immunosuppression­-associated EPF that has been associated with hematologic malignancy EPF (HM-EPF).^3-5

A 69-year-old woman presented with diffusely scattered, pruritic, erythematous, erosive lesions on the back, arms, legs, and forehead (Figure 1) of 4 months’ duration, as well as an ulcerative lesion on the left third toe due to a suspected insect bite. She had a history of untreated CLL that was diagnosed 2 years prior. The patient was empirically started on clindamycin for presumed infection of the toe. A punch biopsy of the left wrist revealed superficial and deep dermal perivascular and interstitial inflammatory infiltrates composed of lymphocytes, histiocytes, and numerous eosinophils in association with edema and necrosis. Histopathology was overall most consistent with an exuberant arthropod reaction; however, at 2-week follow-up, the patient reported that the pustular lesions improved upon starting antibiotics, which raised concerns for a bacterial process. The patient initially was continued on clindamycin given subjective improvement but was later switched to daptomycin, as she developed clindamycin-resistant methicillin-resistant Staphylococcus aureus osteomyelitis from the necrotic toe.

A month later, the patient returned with new papules and pustules on the arms and trunk. A repeat biopsy showed notable dermal collections comprised predominantly of neutrophils and eosinophils as well as involvement of follicular structures by dense inflammation (Figure 2). Immunohistochemistry demonstrated a predominant population of small CD3⁺ T cells, which raised concern for cutaneous T-cell lymphoma. However, retention of CD5 expression made this less likely. Few scattered CD20⁺ B cells with limited CD23 reactivity and without CD5 co-expression were detected, which ruled out cutaneous involvement of the patient’s CLL. Bacterial culture and Grocott methenamine-silver, Gram, acid-fast bacilli, and periodic acid-Schiff stains were negative. Polymerase chain reaction testing for varicella-zoster virus and herpes simplex virus also were negative. Thus, a diagnosis of EPF secondary to CLL was favored, as an infectious process also was unlikely. The patient was started on triamcinolone cream 0.1% with gradual improvement.

Cases of HM-EPF predominantly have been reported in patients who have undergone chemotherapy, bone marrow transplantation, or hematopoietic stem cell transplantation. Furthermore, a vast majority of these cases have been reported in older males.^3-16 In a retrospective study of more than 750 patients with established CLL, Agnew et al⁷ identified 125 different skin complications in 40 patients. Of this subset, only a small number (2/40) were associated with eosinophilic folliculitis, with 1 case noted in a middle-aged woman with a history of CLL treatment.⁷ Moreover, Motaparthi et al⁴ reported 3 additional cases of HM-EPF, with all patients identified as middle-aged men who were treated with chemotherapy for underlying CLL. Our patient represents a case of EPF in the context of untreated CLL in a woman.

Although topical corticosteroids remain the first-line treatment for EPF, a survey study conducted across 67 hospitals in Japan indicated that antibiotics were moderately or highly effective in 79% of EPF patients (n=143).¹⁷ This association may explain the subjective improvement reported by our patient upon starting clindamycin. Furthermore, in HIV-associated EPF, high-dose cetirizine, itraconazole, and metronidazole have been successful when topical therapies have failed.¹⁸ Although the precise pathogenesis of EPF is unknown, histopathologic features, clinical appearance, and identification of the accurate EPF subtype can still prove valuable in informing empiric treatment strategies. Consequently, the initial histopathologic diagnosis of an arthropod bite reaction in our patient highlights the importance of clinical correlation and additional ancillary studies in the determination of EPF vs other inflammatory dermatoses that manifest microscopically with lymphocytic infiltrates, prominent eosinophils, and follicular involvement.⁴ The histopathologic features of EPF demonstrate considerable overlap with eosinophilic dermatosis of hematologic malignancy (also known as eosinophilic dermatosis of myeloproliferative disease). It is suspected that eosinophilic dermatosis of hematologic malignancy and EPF may exist on a spectrum, and additional cases may improve categorization of these entities.¹⁹

In conclusion, this report adds to the medical practitioner’s awareness of EPF manifestations in patients with underlying CLL, an infrequently reported subtype of HM-EPF.

To the Editor:

Eosinophilic pustular folliculitis (EPF) is a noninfectious dermatosis that typically manifests as recurrent follicular papulopustules that generally affect the face and occasionally the trunk and arms. There are several subtypes of EPF: classic EPF (Ofuji disease), infancy-associated EPF, and immunosuppression-associated EPF.^1,2 We report a rare case of EPF in the setting of untreated chronic lymphocytic leukemia (CLL), a subtype of immunosuppression­-associated EPF that has been associated with hematologic malignancy EPF (HM-EPF).^3-5

A 69-year-old woman presented with diffusely scattered, pruritic, erythematous, erosive lesions on the back, arms, legs, and forehead (Figure 1) of 4 months’ duration, as well as an ulcerative lesion on the left third toe due to a suspected insect bite. She had a history of untreated CLL that was diagnosed 2 years prior. The patient was empirically started on clindamycin for presumed infection of the toe. A punch biopsy of the left wrist revealed superficial and deep dermal perivascular and interstitial inflammatory infiltrates composed of lymphocytes, histiocytes, and numerous eosinophils in association with edema and necrosis. Histopathology was overall most consistent with an exuberant arthropod reaction; however, at 2-week follow-up, the patient reported that the pustular lesions improved upon starting antibiotics, which raised concerns for a bacterial process. The patient initially was continued on clindamycin given subjective improvement but was later switched to daptomycin, as she developed clindamycin-resistant methicillin-resistant Staphylococcus aureus osteomyelitis from the necrotic toe.

A month later, the patient returned with new papules and pustules on the arms and trunk. A repeat biopsy showed notable dermal collections comprised predominantly of neutrophils and eosinophils as well as involvement of follicular structures by dense inflammation (Figure 2). Immunohistochemistry demonstrated a predominant population of small CD3⁺ T cells, which raised concern for cutaneous T-cell lymphoma. However, retention of CD5 expression made this less likely. Few scattered CD20⁺ B cells with limited CD23 reactivity and without CD5 co-expression were detected, which ruled out cutaneous involvement of the patient’s CLL. Bacterial culture and Grocott methenamine-silver, Gram, acid-fast bacilli, and periodic acid-Schiff stains were negative. Polymerase chain reaction testing for varicella-zoster virus and herpes simplex virus also were negative. Thus, a diagnosis of EPF secondary to CLL was favored, as an infectious process also was unlikely. The patient was started on triamcinolone cream 0.1% with gradual improvement.

Cases of HM-EPF predominantly have been reported in patients who have undergone chemotherapy, bone marrow transplantation, or hematopoietic stem cell transplantation. Furthermore, a vast majority of these cases have been reported in older males.^3-16 In a retrospective study of more than 750 patients with established CLL, Agnew et al⁷ identified 125 different skin complications in 40 patients. Of this subset, only a small number (2/40) were associated with eosinophilic folliculitis, with 1 case noted in a middle-aged woman with a history of CLL treatment.⁷ Moreover, Motaparthi et al⁴ reported 3 additional cases of HM-EPF, with all patients identified as middle-aged men who were treated with chemotherapy for underlying CLL. Our patient represents a case of EPF in the context of untreated CLL in a woman.

Although topical corticosteroids remain the first-line treatment for EPF, a survey study conducted across 67 hospitals in Japan indicated that antibiotics were moderately or highly effective in 79% of EPF patients (n=143).¹⁷ This association may explain the subjective improvement reported by our patient upon starting clindamycin. Furthermore, in HIV-associated EPF, high-dose cetirizine, itraconazole, and metronidazole have been successful when topical therapies have failed.¹⁸ Although the precise pathogenesis of EPF is unknown, histopathologic features, clinical appearance, and identification of the accurate EPF subtype can still prove valuable in informing empiric treatment strategies. Consequently, the initial histopathologic diagnosis of an arthropod bite reaction in our patient highlights the importance of clinical correlation and additional ancillary studies in the determination of EPF vs other inflammatory dermatoses that manifest microscopically with lymphocytic infiltrates, prominent eosinophils, and follicular involvement.⁴ The histopathologic features of EPF demonstrate considerable overlap with eosinophilic dermatosis of hematologic malignancy (also known as eosinophilic dermatosis of myeloproliferative disease). It is suspected that eosinophilic dermatosis of hematologic malignancy and EPF may exist on a spectrum, and additional cases may improve categorization of these entities.¹⁹

In conclusion, this report adds to the medical practitioner’s awareness of EPF manifestations in patients with underlying CLL, an infrequently reported subtype of HM-EPF.

TOPLINE:

A study found that 94% of best-selling baby cleansers contain allergens, despite their hypoallergenic claims.

METHODOLOGY:

• Many baby cleansers are marketed as “hypoallergenic,” but these claims are not validated. 
• This study assessed the potential allergens and marketing claims in best-selling baby cleansers. 
• The researchers collected ingredients and marketing claims of the top 50 best-selling baby body wash products sold on Amazon on April 4, 2023. 
• Ingredient lists were checked for potential allergens using the 2020 American Contact Dermatitis Society (ACDS) core allergen series, which lists 90 common allergens for adults and children.

TAKEAWAY:

• In the 50 cleansers tested, 10 allergens were identified. Overall, 94% of the cleansers contained at least one allergen, averaging 2.9 allergens per product; cocamidopropyl betaine  (72%), fragrance (64%), and sodium benzoate (54%) were the most common allergens. 
• All cleansers had at least five marketing claims, with an average of 10.9 claims per product; the most common claims were “paraben-free” (88%), “phthalate-free” (84%), “tear-free” (74%), and “hypoallergenic” or “allergy-tested” (74%). 
• There was no significant difference in the number of allergens in the cleansers marketed as “hypoallergenic” or “allergy tested” compared with cleansers that did not have these claims (P = .843).
• Fewer allergens were found in cleansers endorsed by the National Eczema Association (P = .004) or labeled “synthetic fragrance-free” (P = .003).
• There was a positive correlation between a greater number of allergens and an increased number of marketing claims (r = 0.547, P < .001) and a negative correlation between cost and number of allergens (r = −0.450, P = .001).

IN PRACTICE:

Because marketing claims like “hypoallergenic” may be misleading, “clinicians should counsel parents to carefully examine cleanser ingredients or consider selecting cleansers” endorsed by the National Eczema Association or another international eczema organization, especially for infants and children with a history of atopic dermatitis, the authors wrote. 

SOURCE:

The study, led by Sasan D. Noveir, BA, from the University of California, Los Angeles, and coauthors from the division of dermatology at UCLA, was published online in Pediatric Dermatology.

LIMITATIONS:

The study only evaluated top-selling products from a single online source at a specific time, which may limit generalizability. Potential allergens not included in the ACDS core series may be present.

DISCLOSURES:

The study did not disclose any funding source. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

A study found that 94% of best-selling baby cleansers contain allergens, despite their hypoallergenic claims.

METHODOLOGY:

• Many baby cleansers are marketed as “hypoallergenic,” but these claims are not validated. 
• This study assessed the potential allergens and marketing claims in best-selling baby cleansers. 
• The researchers collected ingredients and marketing claims of the top 50 best-selling baby body wash products sold on Amazon on April 4, 2023. 
• Ingredient lists were checked for potential allergens using the 2020 American Contact Dermatitis Society (ACDS) core allergen series, which lists 90 common allergens for adults and children.

TAKEAWAY:

• In the 50 cleansers tested, 10 allergens were identified. Overall, 94% of the cleansers contained at least one allergen, averaging 2.9 allergens per product; cocamidopropyl betaine  (72%), fragrance (64%), and sodium benzoate (54%) were the most common allergens. 
• All cleansers had at least five marketing claims, with an average of 10.9 claims per product; the most common claims were “paraben-free” (88%), “phthalate-free” (84%), “tear-free” (74%), and “hypoallergenic” or “allergy-tested” (74%). 
• There was no significant difference in the number of allergens in the cleansers marketed as “hypoallergenic” or “allergy tested” compared with cleansers that did not have these claims (P = .843).
• Fewer allergens were found in cleansers endorsed by the National Eczema Association (P = .004) or labeled “synthetic fragrance-free” (P = .003).
• There was a positive correlation between a greater number of allergens and an increased number of marketing claims (r = 0.547, P < .001) and a negative correlation between cost and number of allergens (r = −0.450, P = .001).

IN PRACTICE:

Because marketing claims like “hypoallergenic” may be misleading, “clinicians should counsel parents to carefully examine cleanser ingredients or consider selecting cleansers” endorsed by the National Eczema Association or another international eczema organization, especially for infants and children with a history of atopic dermatitis, the authors wrote. 

SOURCE:

The study, led by Sasan D. Noveir, BA, from the University of California, Los Angeles, and coauthors from the division of dermatology at UCLA, was published online in Pediatric Dermatology.

LIMITATIONS:

The study only evaluated top-selling products from a single online source at a specific time, which may limit generalizability. Potential allergens not included in the ACDS core series may be present.

DISCLOSURES:

The study did not disclose any funding source. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

TOPLINE:

A study found that 94% of best-selling baby cleansers contain allergens, despite their hypoallergenic claims.

METHODOLOGY:

• Many baby cleansers are marketed as “hypoallergenic,” but these claims are not validated. 
• This study assessed the potential allergens and marketing claims in best-selling baby cleansers. 
• The researchers collected ingredients and marketing claims of the top 50 best-selling baby body wash products sold on Amazon on April 4, 2023. 
• Ingredient lists were checked for potential allergens using the 2020 American Contact Dermatitis Society (ACDS) core allergen series, which lists 90 common allergens for adults and children.

TAKEAWAY:

• In the 50 cleansers tested, 10 allergens were identified. Overall, 94% of the cleansers contained at least one allergen, averaging 2.9 allergens per product; cocamidopropyl betaine  (72%), fragrance (64%), and sodium benzoate (54%) were the most common allergens. 
• All cleansers had at least five marketing claims, with an average of 10.9 claims per product; the most common claims were “paraben-free” (88%), “phthalate-free” (84%), “tear-free” (74%), and “hypoallergenic” or “allergy-tested” (74%). 
• There was no significant difference in the number of allergens in the cleansers marketed as “hypoallergenic” or “allergy tested” compared with cleansers that did not have these claims (P = .843).
• Fewer allergens were found in cleansers endorsed by the National Eczema Association (P = .004) or labeled “synthetic fragrance-free” (P = .003).
• There was a positive correlation between a greater number of allergens and an increased number of marketing claims (r = 0.547, P < .001) and a negative correlation between cost and number of allergens (r = −0.450, P = .001).

IN PRACTICE:

Because marketing claims like “hypoallergenic” may be misleading, “clinicians should counsel parents to carefully examine cleanser ingredients or consider selecting cleansers” endorsed by the National Eczema Association or another international eczema organization, especially for infants and children with a history of atopic dermatitis, the authors wrote. 

SOURCE:

The study, led by Sasan D. Noveir, BA, from the University of California, Los Angeles, and coauthors from the division of dermatology at UCLA, was published online in Pediatric Dermatology.

LIMITATIONS:

The study only evaluated top-selling products from a single online source at a specific time, which may limit generalizability. Potential allergens not included in the ACDS core series may be present.

DISCLOSURES:

The study did not disclose any funding source. The authors declared no conflicts of interest.

A version of this article appeared on Medscape.com.

Sulfites, present in foods, drinks, pharmaceuticals, and personal care products, have been named the “Allergen of the Year” for 2024 by the American Contact Dermatitis Society (ACDS).

Sulfites are currently not found in most screening patch test series, so may be missed as a relevant contact allergen, Donald V. Belsito, MD, emeritus professor in the Department of Dermatology at Columbia University, New York City, said in his presentation on the Allergen of the Year on March 7 at the annual meeting of the American Contact Dermatitis Society in San Diego. Sulfites, he noted, are distinct from sulfates, and the groups do not cross-react with each other.

FabrikaCr/iStock/Getty Images Plus

Sodium disulfite, an inorganic compound, belongs to a group of sulfiting agents, which contain the sulfite ion SO₃²⁻ and include ammonium sulfite, potassium sulfite, and sodium sulfite, Dr. Belsito said. Sulfites function as antioxidants and preservatives in a range of products including food and beverages, personal care products, and pharmaceuticals.

The type of sulfite allergy diagnosed by patch testing is type IV hypersensitivity or delayed-type hypersensitivity, where patients present with pruritic, red, scaling macules, papulovesicles, and patches, Dr. Belsito told this news organization. “It is not the type I, immediate hypersensitivity that causes hives and, in some cases, anaphylaxis,” he said. Sulfites also can cause these side effects, so correct labeling of food and beverages is important, he noted.

Some common nonoccupational sulfite sources include hair coloring and bleach products, hairspray, tanning lotions, makeup, sunscreens, and deodorants, Dr. Belsito said in his presentation. Medications including topical antifungals, topical corticosteroids, and nasal solutions can be culprits, as can water in swimming pools, he noted.

In occupational settings, sulfites may be present not only in food and drink products but also can be used in production of products, such as those used for sterilization during beer and wine fermentation, Dr. Belsito said. Other potential occupational sources of sulfite exposure include healthcare settings and textile, chemical, rubber, and pharmaceutical manufacturing.

High-sulfite food products (> 100 ppm) to be aware of include dried fruit (raisins and prunes are exceptions), bottled lemon or lime juice (but not frozen products), wine, molasses, grape juice (white, or white, pink, and red sparkling), and pickled cocktail onions, Dr. Belsito said.

“Like other contact allergens, the clinical presentation correlates with exposure,” he added. A study by the North American Contact Dermatitis Group (NACDG) found that 28.8% of patients positive for sulfite allergy on patch testing presented with facial dermatitis, which was not only related to cosmetics and medications used on the face but also from products, such as shampoo, used on the scalp that dripped onto the face. “The scalp is relatively resistant to the expression of contact allergy and may not be involved at all,” he said.

According to the NACDG study, the hands were the second most common site of dermatitis associated with sulfites (20.5%) followed by generalized distribution (13.6%). These sites are to be expected, given the sources of food and beverage, personal care products, and occupational materials, Dr. Belsito said.

“Eczematous dermatitis of the lips is also common in patients with ingested food sources of sulfites,” he said.

Systemic contact dermatitis to sulfites has been documented following oral, rectal, and parental exposure, Dr. Belsito told this news organization. “Systemic dermatitis may present as a scattered/generalized dermatitis, symmetrical drug-related intertriginous and flexural exanthema (also referred to as baboon syndrome), or erythroderma,” he said.
 

How to Spot Sulfite Allergies

The exclusion of sulfites from most patch test series means that sulfite allergy diagnoses are often missed, despite the wide range of potential exposures, Dr. Belsito said.

“Most cases of allergic contact dermatitis occur at the site of application of the allergen,” he noted. Depending on the location of the dermatitis, a detailed history of exposures that includes cosmetics and topical medications, work-related materials, and foods and beverages might suggest a sulfite allergy, he said.

Given the range of potential clinical presentations and the many and varied exposures to sulfites, Dr. Belsito’s best tip for clinicians is to routinely screen for them and evaluate the many avenues of exposure if a patch test is positive, he said.

For now, he said he does not think additional research is needed on sulfites as allergens; instead, sulfites, such as sodium metabisulfite/sodium disulfite, should be included in all clinicians’ baseline screening series, he said.

The Allergen of the Year was also recently announced in the journal Dermatitis. Authors Samuel F. Ekstein, MS, and Erin M. Warshaw, MD, from the Department of Dermatology, Park Nicollet Health Services, Minneapolis, Minnesota, noted that the ACDS hoped to raise awareness of sulfites as a “significant allergen” and called for their increased inclusion in screening patch test series.

Patients identified with sulfite allergies can find alternative products on the ACDS CAMP (Contact Allergen Management Program) website, Dr. Warshaw said in an interview.

She also highlighted some examples of sulfites as allergens in healthcare settings in particular. She described one patient who presented with dermatitis at the site of three previous hand orthopedic procedures.

“Although surgical cleansers were suspected, the patient reacted to sodium metabisulfite. Review of the operating room contactants confirmed sulfites as preservatives in an injectable anesthetic and antibiotic used for wound irrigation,” she said. Another patient who had been treated for recurrent otitis externa and seborrheic dermatitis was found to be allergic to sulfites in an otic antibiotic suspension as well as in a ketoconazole cream product, she added.

In the paper, Dr. Warshaw and Mr. Ekstein called for the addition of sulfites to the test series. Although the NACDG added sodium metabisulfite to the series in 2017, sulfites are not part of the American Contact Dermatitis Core Series, they wrote. Sodium metabisulfite, they said, was added to the European baseline standard series after review of the 2019-2020 patch test reactivity and clinical relevance data.

The ACDS meeting is held every year the day before the annual meeting of the American Academy of Dermatology.

Dr. Belsito and Dr. Warshaw had no financial conflicts to disclose.

A version of this article appeared on Medscape.com.

Sulfites, present in foods, drinks, pharmaceuticals, and personal care products, have been named the “Allergen of the Year” for 2024 by the American Contact Dermatitis Society (ACDS).

Sulfites are currently not found in most screening patch test series, so may be missed as a relevant contact allergen, Donald V. Belsito, MD, emeritus professor in the Department of Dermatology at Columbia University, New York City, said in his presentation on the Allergen of the Year on March 7 at the annual meeting of the American Contact Dermatitis Society in San Diego. Sulfites, he noted, are distinct from sulfates, and the groups do not cross-react with each other.

FabrikaCr/iStock/Getty Images Plus

Sodium disulfite, an inorganic compound, belongs to a group of sulfiting agents, which contain the sulfite ion SO₃²⁻ and include ammonium sulfite, potassium sulfite, and sodium sulfite, Dr. Belsito said. Sulfites function as antioxidants and preservatives in a range of products including food and beverages, personal care products, and pharmaceuticals.

The type of sulfite allergy diagnosed by patch testing is type IV hypersensitivity or delayed-type hypersensitivity, where patients present with pruritic, red, scaling macules, papulovesicles, and patches, Dr. Belsito told this news organization. “It is not the type I, immediate hypersensitivity that causes hives and, in some cases, anaphylaxis,” he said. Sulfites also can cause these side effects, so correct labeling of food and beverages is important, he noted.

Some common nonoccupational sulfite sources include hair coloring and bleach products, hairspray, tanning lotions, makeup, sunscreens, and deodorants, Dr. Belsito said in his presentation. Medications including topical antifungals, topical corticosteroids, and nasal solutions can be culprits, as can water in swimming pools, he noted.

In occupational settings, sulfites may be present not only in food and drink products but also can be used in production of products, such as those used for sterilization during beer and wine fermentation, Dr. Belsito said. Other potential occupational sources of sulfite exposure include healthcare settings and textile, chemical, rubber, and pharmaceutical manufacturing.

High-sulfite food products (> 100 ppm) to be aware of include dried fruit (raisins and prunes are exceptions), bottled lemon or lime juice (but not frozen products), wine, molasses, grape juice (white, or white, pink, and red sparkling), and pickled cocktail onions, Dr. Belsito said.

“Like other contact allergens, the clinical presentation correlates with exposure,” he added. A study by the North American Contact Dermatitis Group (NACDG) found that 28.8% of patients positive for sulfite allergy on patch testing presented with facial dermatitis, which was not only related to cosmetics and medications used on the face but also from products, such as shampoo, used on the scalp that dripped onto the face. “The scalp is relatively resistant to the expression of contact allergy and may not be involved at all,” he said.

According to the NACDG study, the hands were the second most common site of dermatitis associated with sulfites (20.5%) followed by generalized distribution (13.6%). These sites are to be expected, given the sources of food and beverage, personal care products, and occupational materials, Dr. Belsito said.

“Eczematous dermatitis of the lips is also common in patients with ingested food sources of sulfites,” he said.

Systemic contact dermatitis to sulfites has been documented following oral, rectal, and parental exposure, Dr. Belsito told this news organization. “Systemic dermatitis may present as a scattered/generalized dermatitis, symmetrical drug-related intertriginous and flexural exanthema (also referred to as baboon syndrome), or erythroderma,” he said.
 

How to Spot Sulfite Allergies

The exclusion of sulfites from most patch test series means that sulfite allergy diagnoses are often missed, despite the wide range of potential exposures, Dr. Belsito said.

“Most cases of allergic contact dermatitis occur at the site of application of the allergen,” he noted. Depending on the location of the dermatitis, a detailed history of exposures that includes cosmetics and topical medications, work-related materials, and foods and beverages might suggest a sulfite allergy, he said.

Given the range of potential clinical presentations and the many and varied exposures to sulfites, Dr. Belsito’s best tip for clinicians is to routinely screen for them and evaluate the many avenues of exposure if a patch test is positive, he said.

For now, he said he does not think additional research is needed on sulfites as allergens; instead, sulfites, such as sodium metabisulfite/sodium disulfite, should be included in all clinicians’ baseline screening series, he said.

The Allergen of the Year was also recently announced in the journal Dermatitis. Authors Samuel F. Ekstein, MS, and Erin M. Warshaw, MD, from the Department of Dermatology, Park Nicollet Health Services, Minneapolis, Minnesota, noted that the ACDS hoped to raise awareness of sulfites as a “significant allergen” and called for their increased inclusion in screening patch test series.

Patients identified with sulfite allergies can find alternative products on the ACDS CAMP (Contact Allergen Management Program) website, Dr. Warshaw said in an interview.

She also highlighted some examples of sulfites as allergens in healthcare settings in particular. She described one patient who presented with dermatitis at the site of three previous hand orthopedic procedures.

“Although surgical cleansers were suspected, the patient reacted to sodium metabisulfite. Review of the operating room contactants confirmed sulfites as preservatives in an injectable anesthetic and antibiotic used for wound irrigation,” she said. Another patient who had been treated for recurrent otitis externa and seborrheic dermatitis was found to be allergic to sulfites in an otic antibiotic suspension as well as in a ketoconazole cream product, she added.

In the paper, Dr. Warshaw and Mr. Ekstein called for the addition of sulfites to the test series. Although the NACDG added sodium metabisulfite to the series in 2017, sulfites are not part of the American Contact Dermatitis Core Series, they wrote. Sodium metabisulfite, they said, was added to the European baseline standard series after review of the 2019-2020 patch test reactivity and clinical relevance data.

The ACDS meeting is held every year the day before the annual meeting of the American Academy of Dermatology.

Dr. Belsito and Dr. Warshaw had no financial conflicts to disclose.

A version of this article appeared on Medscape.com.

Sulfites, present in foods, drinks, pharmaceuticals, and personal care products, have been named the “Allergen of the Year” for 2024 by the American Contact Dermatitis Society (ACDS).

Sulfites are currently not found in most screening patch test series, so may be missed as a relevant contact allergen, Donald V. Belsito, MD, emeritus professor in the Department of Dermatology at Columbia University, New York City, said in his presentation on the Allergen of the Year on March 7 at the annual meeting of the American Contact Dermatitis Society in San Diego. Sulfites, he noted, are distinct from sulfates, and the groups do not cross-react with each other.

FabrikaCr/iStock/Getty Images Plus

Sodium disulfite, an inorganic compound, belongs to a group of sulfiting agents, which contain the sulfite ion SO₃²⁻ and include ammonium sulfite, potassium sulfite, and sodium sulfite, Dr. Belsito said. Sulfites function as antioxidants and preservatives in a range of products including food and beverages, personal care products, and pharmaceuticals.

The type of sulfite allergy diagnosed by patch testing is type IV hypersensitivity or delayed-type hypersensitivity, where patients present with pruritic, red, scaling macules, papulovesicles, and patches, Dr. Belsito told this news organization. “It is not the type I, immediate hypersensitivity that causes hives and, in some cases, anaphylaxis,” he said. Sulfites also can cause these side effects, so correct labeling of food and beverages is important, he noted.

Some common nonoccupational sulfite sources include hair coloring and bleach products, hairspray, tanning lotions, makeup, sunscreens, and deodorants, Dr. Belsito said in his presentation. Medications including topical antifungals, topical corticosteroids, and nasal solutions can be culprits, as can water in swimming pools, he noted.

In occupational settings, sulfites may be present not only in food and drink products but also can be used in production of products, such as those used for sterilization during beer and wine fermentation, Dr. Belsito said. Other potential occupational sources of sulfite exposure include healthcare settings and textile, chemical, rubber, and pharmaceutical manufacturing.

High-sulfite food products (> 100 ppm) to be aware of include dried fruit (raisins and prunes are exceptions), bottled lemon or lime juice (but not frozen products), wine, molasses, grape juice (white, or white, pink, and red sparkling), and pickled cocktail onions, Dr. Belsito said.

“Like other contact allergens, the clinical presentation correlates with exposure,” he added. A study by the North American Contact Dermatitis Group (NACDG) found that 28.8% of patients positive for sulfite allergy on patch testing presented with facial dermatitis, which was not only related to cosmetics and medications used on the face but also from products, such as shampoo, used on the scalp that dripped onto the face. “The scalp is relatively resistant to the expression of contact allergy and may not be involved at all,” he said.

According to the NACDG study, the hands were the second most common site of dermatitis associated with sulfites (20.5%) followed by generalized distribution (13.6%). These sites are to be expected, given the sources of food and beverage, personal care products, and occupational materials, Dr. Belsito said.

“Eczematous dermatitis of the lips is also common in patients with ingested food sources of sulfites,” he said.

Systemic contact dermatitis to sulfites has been documented following oral, rectal, and parental exposure, Dr. Belsito told this news organization. “Systemic dermatitis may present as a scattered/generalized dermatitis, symmetrical drug-related intertriginous and flexural exanthema (also referred to as baboon syndrome), or erythroderma,” he said.
 

How to Spot Sulfite Allergies

The exclusion of sulfites from most patch test series means that sulfite allergy diagnoses are often missed, despite the wide range of potential exposures, Dr. Belsito said.

“Most cases of allergic contact dermatitis occur at the site of application of the allergen,” he noted. Depending on the location of the dermatitis, a detailed history of exposures that includes cosmetics and topical medications, work-related materials, and foods and beverages might suggest a sulfite allergy, he said.

Given the range of potential clinical presentations and the many and varied exposures to sulfites, Dr. Belsito’s best tip for clinicians is to routinely screen for them and evaluate the many avenues of exposure if a patch test is positive, he said.

For now, he said he does not think additional research is needed on sulfites as allergens; instead, sulfites, such as sodium metabisulfite/sodium disulfite, should be included in all clinicians’ baseline screening series, he said.

The Allergen of the Year was also recently announced in the journal Dermatitis. Authors Samuel F. Ekstein, MS, and Erin M. Warshaw, MD, from the Department of Dermatology, Park Nicollet Health Services, Minneapolis, Minnesota, noted that the ACDS hoped to raise awareness of sulfites as a “significant allergen” and called for their increased inclusion in screening patch test series.

Patients identified with sulfite allergies can find alternative products on the ACDS CAMP (Contact Allergen Management Program) website, Dr. Warshaw said in an interview.

She also highlighted some examples of sulfites as allergens in healthcare settings in particular. She described one patient who presented with dermatitis at the site of three previous hand orthopedic procedures.

“Although surgical cleansers were suspected, the patient reacted to sodium metabisulfite. Review of the operating room contactants confirmed sulfites as preservatives in an injectable anesthetic and antibiotic used for wound irrigation,” she said. Another patient who had been treated for recurrent otitis externa and seborrheic dermatitis was found to be allergic to sulfites in an otic antibiotic suspension as well as in a ketoconazole cream product, she added.

In the paper, Dr. Warshaw and Mr. Ekstein called for the addition of sulfites to the test series. Although the NACDG added sodium metabisulfite to the series in 2017, sulfites are not part of the American Contact Dermatitis Core Series, they wrote. Sodium metabisulfite, they said, was added to the European baseline standard series after review of the 2019-2020 patch test reactivity and clinical relevance data.

The ACDS meeting is held every year the day before the annual meeting of the American Academy of Dermatology.

Dr. Belsito and Dr. Warshaw had no financial conflicts to disclose.

A version of this article appeared on Medscape.com.

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.

Carpet beetle larvae of the family Dermestidae have been documented to cause both acute and delayed hypersensitivity reactions in susceptible individuals. These larvae have specialized horizontal rows of spear-shaped hairs called hastisetae, which detach easily into the surrounding environment and are small enough to travel by air. Exposure to hastisetae has been tied to adverse effects ranging from dermatitis to rhinoconjunctivitis and acute asthma, with treatment being mostly empiric and symptom based. Due to the pervasiveness of carpet beetles in homes, improved awareness of dermestid-induced manifestations is valuable for clinicians.

Beetles in the Dermestidae family do not bite humans but have been reported to cause skin reactions in addition to other symptoms typical of an allergic reaction. Skin contact with larval hairs (hastisetae) of these insects—known as carpet, larder, or hide beetles — may cause urticarial or edematous papules that are mistaken for papular urticaria or arthropod bites. ¹ There are approximately 500 to 700 species of carpet beetles worldwide. Carpet beetles are a clinically underrecognized cause of allergic contact dermatitis given their frequent presence in homes across the world. ² Carpet beetle larvae feed on shed skin, feathers, hair, wool, book bindings, felt, leather, wood, silk, and sometimes grains and thus can be found nearly anywhere. Most symptom-inducing exposures to Dermestidae beetles occur occupationally, such as in museum curators working hands-on with collection materials and workers handling infested materials such as wool. ^3,4 In-home Dermestidae exposure may lead to symptoms, especially if regularly worn clothing and bedding materials are infested. The broad palate of dermestid members has resulted in substantial contamination of stored materials such as flour and fabric in addition to the destruction of museum collections. ^5-7

The larvae of some dermestid species, most commonly of the genera Anthrenus and Dermestes, are 2 to 3 mm in length and have detachable hairlike hastisetae that shed into the surrounding environment throughout larval development (Figure 1).⁸ The hastisetae, located on the thoracic and abdominal segments (tergites), serve as a larval defense mechanism. When prodded, the round, hairy, wormlike larvae tense up and can raise their abdominal tergites while splaying the hastisetae out in a fanlike manner.⁹ Similar to porcupine quills, the hastisetae easily detach and can entrap the appendages of invertebrate predators. Hastisetae are not known to be sharp enough to puncture human skin, but friction and irritation from skin contact and superficial sticking of the hastisetae into mucous membranes and noncornified epithelium, such as in the bronchial airways, are thought to induce hypersensitivity reactions in susceptible individuals.

Additionally, hastisetae and the exoskeletons of both adult and larval dermestid beetles are composed mostly of chitin, which is highly allergenic. Chitin has been found to play a proinflammatory role in ocular inflammation, asthma, and bronchial reactivity via T helper cell (T_H2)–mediated cellular interactions.^10-12 Larvae shed their exoskeletons, including hastisetae, multiple times over the course of their development, which contributes to their potential allergen burden (Figure 2). Reports of positive prick and/or patch testing to larval components indicate some cases of both acute type 1 and delayed type 4 hypersensitivity reactions.^4,8,13

Clinical Presentation and Diagnosis

Multiple erythematous urticarial papules, papulopustules, and papulovesicles are the typical manifestations of dermestid dermatitis.^3,4,13-16 Figure 3 demonstrates several characteristic edematous papules with background erythema. Unlike the clusters seen with flea and bed bug bites, dermestid-induced lesions typically are single and scattered, with a propensity for exposed limbs and the face. Exposure to hastisetae commonly results in classic allergic symptoms including rhinitis, conjunctivitis, coughing, wheezing, sneezing, and intranasal and periocular pruritus, even in those with no personal history of atopy.^17-19 Lymphadenopathy, vasculitis, and allergic alveolitis also have been reported.²⁰ A large infestation in which many individual beetles as well as larvae can be found in 1 or more areas of the inhabited structure has been reported to cause more severe symptoms, including acute eczema, otitis externa, lymphocytic vasculitis, and allergic alveolitis, all of which resolved within 3 months of thorough deinfestation cleaning.²¹

Skin-prick and/or patch testing is not necessary for this clinical diagnosis of dermestid-induced allergic contact dermatitis. This diagnosis is bolstered by (but does not require a history of) repeated symptom induction upon performing certain activities (eg, handling taxidermy specimens) and/or in certain environments (eg, only at home). Because of individual differences in hypersensitivity to dermestid parts, it is not typical for all members of a household to be affected.

When there are multiple potential suspected allergens or an unknown cause for symptoms despite a detailed history, allergy testing can be useful in confirming a diagnosis and directing management. Immediate-onset type 1 hypersensitivity reactions are evaluated using skin-prick testing or serum IgE levels, whereas delayed type 4 hypersensitivity reactions can be evaluated using patch testing. Type 1 reactions tend to present with classic allergy symptoms, especially where there are abundant mast cells to degranulate in the skin and mucosa of the gastrointestinal and respiratory tracts; these symptoms range from mild wheezing, urticaria, periorbital pruritus, and sneezing to outright asthma, diarrhea, rhinoconjunctivitis, and even anaphylaxis. With these reactions, initial exposure to an antigen such as chitin in the hastisetae leads to an asymptomatic sensitization against the antigen in which its introduction leads to a T_H2-skewed cellular response, which promotes B-cell production of IgE antibodies. Upon subsequent exposure to this antigen, IgE antibodies bound to mast cells will lead them to degranulate with release of histamine and other proinflammatory molecules, resulting in clinical manifestations. The skin-prick test relies on introduction of potential antigens through the epidermis into the dermis with a sharp lancet to induce IgE antibody activation and then degranulation of the patient’s mast cells, resulting in a pruritic erythematous wheal. This IgE-mediated process has been shown to occur in response to dermestid larval parts among household dust, resulting in chronic coughing, sneezing, nasal pruritus, and asthma.^15,17,22

Type 4 hypersensitivity reactions are T-cell mediated and also include a sensitization phase followed by symptom manifestation upon repeat exposure; however, these reactions usually are not immediate and can take up to 72 hours after exposure to manifest.²³ This is because T cells specific to the antigen do not lead a process resulting in antibodies but instead recruit numerous other T_H1-polarized mediators upon re-exposure to activate cytotoxic CD8⁺ T cells and macrophages to attempt to neutralize the antigen. Many type 4 reactions result in mostly cutaneous manifestations, such as contact dermatitis. Patch testing involves adhering potential allergens to the skin for a time with assessments at regular intervals to evaluate the level of reaction from weakly positive to severe. At minimum, most reports of dermestid-related manifestations include a rash such as erythematous papules, and several published cases involving patch testing have yielded positive results to various preparations of larval parts.^3,14,21

Management and Treatment

Prevention of dermestid exposure is difficult given the myriad materials eaten by the larvae. An insect exterminator should verify and treat a carpet beetle infestation, while a dermatologist can treat symptomatic individuals. Treatment is driven by the severity of the patient’s discomfort and is aimed at both symptomatic relief and reducing dermestid exposure moving forward. Although in certain environments it will be nearly impossible to eradicate Dermestidae, cleaning thoroughly and regularly may go far to reduce exposure and associated symptoms.

Clothing and other materials such as bedding that will have direct skin contact should be washed to remove hastisetae and be stored in airtight containers in addition to items made with animal fibers, such as wool sweaters and down blankets. Mattresses, flooring, rugs, curtains, and other amenable areas should be vacuumed thoroughly, and the vacuum bag should be placed in the trash afterward. Protective pillow and mattress covers should be used. Stuffed animals in infested areas should be thrown away if not able to be completely washed and dried. Air conditioning systems may spread larval hairs away from the site of infestation and should be cleaned as much as possible. Surfaces where beetles and larvae also are commonly seen, such as windowsills, and hidden among closet and pantry items should also be wiped clean to remove both insects and potential substrate. In one case, scraping the wood flooring and applying a thick coat of varnish in addition to removing all stuffed animals from an affected individual’s home allowed for resolution of symptoms.¹⁷

Treatment for symptoms includes topical anti-inflammatory agents and/or oral antihistamines, with improvement in symptoms typically occurring within days and resolution dependent on level of exposure moving forward.

Final Thoughts

There is a broad overlap between dermestid habitats and human-occupied environments; thus, the opportunities for exposure and sensitization to allergenic dermestid parts are numerous. Dermatologists should be aware of the possible manifestations from dermestid exposure.

To the Editor:

Cellulitis is the most common reason for skin-related hospital admissions.¹ Despite its frequency, it is suspected that many cases of cellulitis are misdiagnosed as other etiologies presenting with similar symptoms such as a ruptured Baker cyst. These cysts are located behind the knee and can present with calf pain, peripheral edema, and erythema when ruptured. Symptoms of a ruptured Baker cyst can be indistinguishable from cellulitis as well as deep vein thrombosis (DVT), both manifesting with lower extremity pain, swelling, and erythema, making diagnosis challenging.² The hemorrhagic crescent sign—a crescent of ecchymosis distal to the medial malleolus and on the foot that results from synovial injury or rupture—can be a useful diagnostic tool to differentiate between the causes of acute swelling and pain of the leg.² When observed, the hemorrhagic crescent sign supports testing for synovial pathology at the knee.

A 63-year-old man presented to an outside hospital for evaluation of a fever (temperature, 101 °F [38.3 °C]), as well as pain, edema, and erythema of the right lower leg of 2 days’ duration. He had a history of leg cellulitis, gout, diabetes mellitus, lymphedema, and peripheral neuropathy. On admission, he was found to have elevated C-reactive protein (45 mg/L [reference range, <8 mg/L]) and mild leukocytosis (13,500 cells/μL [reference range, 4500–11,000 cells/μL]). A venous duplex scan did not demonstrate signs of thrombosis. Antibiotic therapy was started for suspected cellulitis including levofloxacin, piperacillin-tazobactam, and linezolid. Despite broad-spectrum antibiotic coverage, the patient continued to be febrile and experienced progressive erythema and swelling of the right lower leg, at which point he was transferred to our institution. A new antibiotic regimen of vancomycin, cefepime, and clindamycin was started and showed no improvement, after which dermatology was consulted.

Physical examination revealed unilateral edema and calor of the right lower leg with a demarcated erythematous rash extending to the level of the knee. Furthermore, a hemorrhagic crescent sign was present below the right medial malleolus (Figure). The popliteal fossa was supple, though the patient was adamant that he had a Baker cyst. Punch biopsies demonstrated epidermal spongiosis and extensive edema with perivascular inflammation. No organisms were found by stain and culture. Ultrasound records confirmed a Baker cyst present at least 4 months prior; however, a repeat ultrasound showed resolution. A diagnosis of pseudocellulitis secondary to Baker cyst rupture was made, and corticosteroids were started, resulting in marked reduction in erythema and edema of the lower leg and hospital discharge.

This case highlights the importance of early involvement of dermatology when cellulitis is suspected. A study of 635 patients in the United Kingdom referred to dermatology for lower limb cellulitis found that 210 (33%) patients did not have cellulitis and only 18 (3%) required hospital admission.³ Dermatology consultations have been shown to benefit patients with inflammatory skin disease by decreasing length of stay and reducing readmissions.⁴

Our patient had several risk factors for cellulitis, including obesity, lymphedema, and chronic kidney disease, in addition to having fevers and unilateral involvement. However, failure of symptoms to improve with broad-spectrum antibiotics made a diagnosis of cellulitis less likely. In this case, a severe immune response to the ruptured Baker cyst mimicked the presentation of cellulitis.

Ruptured Baker cysts have been reported to cause acute leg swelling, mimicking the symptoms of cellulitis or DVT.^2,5 The presence of a hemorrhagic crescent sign can be a useful diagnostic tool, as in our patient, because it has been reported as an indication of synovial injury or rupture, supporting the exclusion of cellulitis or DVT when it is observed.⁶ Prior reports have observed ecchymosis on the foot in as little as 1 day after the onset of calf swelling and at the lateral malleolus 3 days after the onset of calf swelling.⁵

Following suspicion of a ruptured Baker cyst causing pseudocellulitis, an ultrasound can be used to confirm the diagnosis. Ultrasonography shows a large hypoechoic space behind the calf muscles, which is pathognomonic of a ruptured Baker cyst.⁷

In conclusion, when a hemorrhagic crescent sign is observed, one should be suspicious for a ruptured Baker cyst or other synovial pathology as an etiology of pseudocellulitis. Early recognition of the hemorrhagic crescent sign can help rule out cellulitis and DVT, thereby reducing the amount of intravenous antibiotic prescribed, decreasing the length of hospital stay, and reducing readmission.

To the Editor:

Cellulitis is the most common reason for skin-related hospital admissions.¹ Despite its frequency, it is suspected that many cases of cellulitis are misdiagnosed as other etiologies presenting with similar symptoms such as a ruptured Baker cyst. These cysts are located behind the knee and can present with calf pain, peripheral edema, and erythema when ruptured. Symptoms of a ruptured Baker cyst can be indistinguishable from cellulitis as well as deep vein thrombosis (DVT), both manifesting with lower extremity pain, swelling, and erythema, making diagnosis challenging.² The hemorrhagic crescent sign—a crescent of ecchymosis distal to the medial malleolus and on the foot that results from synovial injury or rupture—can be a useful diagnostic tool to differentiate between the causes of acute swelling and pain of the leg.² When observed, the hemorrhagic crescent sign supports testing for synovial pathology at the knee.

A 63-year-old man presented to an outside hospital for evaluation of a fever (temperature, 101 °F [38.3 °C]), as well as pain, edema, and erythema of the right lower leg of 2 days’ duration. He had a history of leg cellulitis, gout, diabetes mellitus, lymphedema, and peripheral neuropathy. On admission, he was found to have elevated C-reactive protein (45 mg/L [reference range, <8 mg/L]) and mild leukocytosis (13,500 cells/μL [reference range, 4500–11,000 cells/μL]). A venous duplex scan did not demonstrate signs of thrombosis. Antibiotic therapy was started for suspected cellulitis including levofloxacin, piperacillin-tazobactam, and linezolid. Despite broad-spectrum antibiotic coverage, the patient continued to be febrile and experienced progressive erythema and swelling of the right lower leg, at which point he was transferred to our institution. A new antibiotic regimen of vancomycin, cefepime, and clindamycin was started and showed no improvement, after which dermatology was consulted.

Physical examination revealed unilateral edema and calor of the right lower leg with a demarcated erythematous rash extending to the level of the knee. Furthermore, a hemorrhagic crescent sign was present below the right medial malleolus (Figure). The popliteal fossa was supple, though the patient was adamant that he had a Baker cyst. Punch biopsies demonstrated epidermal spongiosis and extensive edema with perivascular inflammation. No organisms were found by stain and culture. Ultrasound records confirmed a Baker cyst present at least 4 months prior; however, a repeat ultrasound showed resolution. A diagnosis of pseudocellulitis secondary to Baker cyst rupture was made, and corticosteroids were started, resulting in marked reduction in erythema and edema of the lower leg and hospital discharge.

This case highlights the importance of early involvement of dermatology when cellulitis is suspected. A study of 635 patients in the United Kingdom referred to dermatology for lower limb cellulitis found that 210 (33%) patients did not have cellulitis and only 18 (3%) required hospital admission.³ Dermatology consultations have been shown to benefit patients with inflammatory skin disease by decreasing length of stay and reducing readmissions.⁴

Our patient had several risk factors for cellulitis, including obesity, lymphedema, and chronic kidney disease, in addition to having fevers and unilateral involvement. However, failure of symptoms to improve with broad-spectrum antibiotics made a diagnosis of cellulitis less likely. In this case, a severe immune response to the ruptured Baker cyst mimicked the presentation of cellulitis.

Ruptured Baker cysts have been reported to cause acute leg swelling, mimicking the symptoms of cellulitis or DVT.^2,5 The presence of a hemorrhagic crescent sign can be a useful diagnostic tool, as in our patient, because it has been reported as an indication of synovial injury or rupture, supporting the exclusion of cellulitis or DVT when it is observed.⁶ Prior reports have observed ecchymosis on the foot in as little as 1 day after the onset of calf swelling and at the lateral malleolus 3 days after the onset of calf swelling.⁵

Following suspicion of a ruptured Baker cyst causing pseudocellulitis, an ultrasound can be used to confirm the diagnosis. Ultrasonography shows a large hypoechoic space behind the calf muscles, which is pathognomonic of a ruptured Baker cyst.⁷

In conclusion, when a hemorrhagic crescent sign is observed, one should be suspicious for a ruptured Baker cyst or other synovial pathology as an etiology of pseudocellulitis. Early recognition of the hemorrhagic crescent sign can help rule out cellulitis and DVT, thereby reducing the amount of intravenous antibiotic prescribed, decreasing the length of hospital stay, and reducing readmission.

To the Editor:

Cellulitis is the most common reason for skin-related hospital admissions.¹ Despite its frequency, it is suspected that many cases of cellulitis are misdiagnosed as other etiologies presenting with similar symptoms such as a ruptured Baker cyst. These cysts are located behind the knee and can present with calf pain, peripheral edema, and erythema when ruptured. Symptoms of a ruptured Baker cyst can be indistinguishable from cellulitis as well as deep vein thrombosis (DVT), both manifesting with lower extremity pain, swelling, and erythema, making diagnosis challenging.² The hemorrhagic crescent sign—a crescent of ecchymosis distal to the medial malleolus and on the foot that results from synovial injury or rupture—can be a useful diagnostic tool to differentiate between the causes of acute swelling and pain of the leg.² When observed, the hemorrhagic crescent sign supports testing for synovial pathology at the knee.

A 63-year-old man presented to an outside hospital for evaluation of a fever (temperature, 101 °F [38.3 °C]), as well as pain, edema, and erythema of the right lower leg of 2 days’ duration. He had a history of leg cellulitis, gout, diabetes mellitus, lymphedema, and peripheral neuropathy. On admission, he was found to have elevated C-reactive protein (45 mg/L [reference range, <8 mg/L]) and mild leukocytosis (13,500 cells/μL [reference range, 4500–11,000 cells/μL]). A venous duplex scan did not demonstrate signs of thrombosis. Antibiotic therapy was started for suspected cellulitis including levofloxacin, piperacillin-tazobactam, and linezolid. Despite broad-spectrum antibiotic coverage, the patient continued to be febrile and experienced progressive erythema and swelling of the right lower leg, at which point he was transferred to our institution. A new antibiotic regimen of vancomycin, cefepime, and clindamycin was started and showed no improvement, after which dermatology was consulted.

Physical examination revealed unilateral edema and calor of the right lower leg with a demarcated erythematous rash extending to the level of the knee. Furthermore, a hemorrhagic crescent sign was present below the right medial malleolus (Figure). The popliteal fossa was supple, though the patient was adamant that he had a Baker cyst. Punch biopsies demonstrated epidermal spongiosis and extensive edema with perivascular inflammation. No organisms were found by stain and culture. Ultrasound records confirmed a Baker cyst present at least 4 months prior; however, a repeat ultrasound showed resolution. A diagnosis of pseudocellulitis secondary to Baker cyst rupture was made, and corticosteroids were started, resulting in marked reduction in erythema and edema of the lower leg and hospital discharge.

This case highlights the importance of early involvement of dermatology when cellulitis is suspected. A study of 635 patients in the United Kingdom referred to dermatology for lower limb cellulitis found that 210 (33%) patients did not have cellulitis and only 18 (3%) required hospital admission.³ Dermatology consultations have been shown to benefit patients with inflammatory skin disease by decreasing length of stay and reducing readmissions.⁴

Our patient had several risk factors for cellulitis, including obesity, lymphedema, and chronic kidney disease, in addition to having fevers and unilateral involvement. However, failure of symptoms to improve with broad-spectrum antibiotics made a diagnosis of cellulitis less likely. In this case, a severe immune response to the ruptured Baker cyst mimicked the presentation of cellulitis.

Ruptured Baker cysts have been reported to cause acute leg swelling, mimicking the symptoms of cellulitis or DVT.^2,5 The presence of a hemorrhagic crescent sign can be a useful diagnostic tool, as in our patient, because it has been reported as an indication of synovial injury or rupture, supporting the exclusion of cellulitis or DVT when it is observed.⁶ Prior reports have observed ecchymosis on the foot in as little as 1 day after the onset of calf swelling and at the lateral malleolus 3 days after the onset of calf swelling.⁵

Following suspicion of a ruptured Baker cyst causing pseudocellulitis, an ultrasound can be used to confirm the diagnosis. Ultrasonography shows a large hypoechoic space behind the calf muscles, which is pathognomonic of a ruptured Baker cyst.⁷

In conclusion, when a hemorrhagic crescent sign is observed, one should be suspicious for a ruptured Baker cyst or other synovial pathology as an etiology of pseudocellulitis. Early recognition of the hemorrhagic crescent sign can help rule out cellulitis and DVT, thereby reducing the amount of intravenous antibiotic prescribed, decreasing the length of hospital stay, and reducing readmission.

The Diagnosis: Gastric Acid Dermatitis

After further discussion, the patient indicated that he had vomited during the night of alcohol consumption, and the vomitus remained on the affected areas until the next morning, indicating that excessive alcohol ingestion stimulated abundant secretion of gastric acid, which caused the symptoms. Additionally, the presence of clothing acted as a buffer in the unaffected areas, which helped make the final diagnosis of gastric acid dermatitis. The patient was treated with external application of recombinant bovine basic fibroblast growth factor gel (21,000 IU/5 g) once daily, and the lesions greatly improved within 7 days. The burning pain of the throat, stomach, and esophagus resolved after consultation with an otolaryngologist and a gastroenterologist.

Gastric acid dermatitis is a new term used to describe an acute skin burn caused by the patient's own gastric acid. Generally, the pH of human gastric acid is between 0.9 and 1.8 but will be diluted after eating and will gradually increase to approximately 3.5, which is not enough to induce burns on the skin.¹ In addition, the skin barrier is capable of preventing transient gastric acid corrosion.^2,3 However, the release of a large amount of gastric acid after excessive alcohol ingestion coupled with 1 night of lethargy left enough acid and time to induce skin burns in our patient.

Dermatitis caused by other allergic or chemical factors, such as Paederus dermatitis, was excluded, as the patient’s manifestation occurred during the inactive period of Paederus fuscipes. Furthermore, the patient denied any history of contact with chemicals in the last month. Food eruptions primarily manifest as systemic anaphylaxis with eruptive and pruritic rashes after consumption of seafood, eggs, milk, or other proteins, while alcoholic contact dermatitis is a form of irritating dermatitis that could be easily induced again by direct skin contact with alcohol.

Management of gastric acid dermatitis is similar to that for other chemical burns. Because scarring seldom occurs, the central issue is to restore the skin barrier as quickly as possible and to avoid or alleviate postinflammatory hyperpigmentation. Treatments to restore the skin barrier include recombinant bovine or human-derived basic fibroblast growth factor gel, moist exposed burn ointment, and medical sodium hyaluronate gelatin. To treat postinflammatory hyperpigmentation, some whitening agents such as compound superoxide dismutase arbutin cream and hydroquinone cream as well as the Q-switched Nd:YAG laser are effective to ameliorate the skin condition. If skin burns are on sun-exposed areas, photoprotection is necessary to prevent hyperpigmentation.

Acknowledgment—We thank the patient for granting permission to publish this information.

The Diagnosis: Gastric Acid Dermatitis

After further discussion, the patient indicated that he had vomited during the night of alcohol consumption, and the vomitus remained on the affected areas until the next morning, indicating that excessive alcohol ingestion stimulated abundant secretion of gastric acid, which caused the symptoms. Additionally, the presence of clothing acted as a buffer in the unaffected areas, which helped make the final diagnosis of gastric acid dermatitis. The patient was treated with external application of recombinant bovine basic fibroblast growth factor gel (21,000 IU/5 g) once daily, and the lesions greatly improved within 7 days. The burning pain of the throat, stomach, and esophagus resolved after consultation with an otolaryngologist and a gastroenterologist.

Gastric acid dermatitis is a new term used to describe an acute skin burn caused by the patient's own gastric acid. Generally, the pH of human gastric acid is between 0.9 and 1.8 but will be diluted after eating and will gradually increase to approximately 3.5, which is not enough to induce burns on the skin.¹ In addition, the skin barrier is capable of preventing transient gastric acid corrosion.^2,3 However, the release of a large amount of gastric acid after excessive alcohol ingestion coupled with 1 night of lethargy left enough acid and time to induce skin burns in our patient.

Dermatitis caused by other allergic or chemical factors, such as Paederus dermatitis, was excluded, as the patient’s manifestation occurred during the inactive period of Paederus fuscipes. Furthermore, the patient denied any history of contact with chemicals in the last month. Food eruptions primarily manifest as systemic anaphylaxis with eruptive and pruritic rashes after consumption of seafood, eggs, milk, or other proteins, while alcoholic contact dermatitis is a form of irritating dermatitis that could be easily induced again by direct skin contact with alcohol.

Management of gastric acid dermatitis is similar to that for other chemical burns. Because scarring seldom occurs, the central issue is to restore the skin barrier as quickly as possible and to avoid or alleviate postinflammatory hyperpigmentation. Treatments to restore the skin barrier include recombinant bovine or human-derived basic fibroblast growth factor gel, moist exposed burn ointment, and medical sodium hyaluronate gelatin. To treat postinflammatory hyperpigmentation, some whitening agents such as compound superoxide dismutase arbutin cream and hydroquinone cream as well as the Q-switched Nd:YAG laser are effective to ameliorate the skin condition. If skin burns are on sun-exposed areas, photoprotection is necessary to prevent hyperpigmentation.

Acknowledgment—We thank the patient for granting permission to publish this information.

The Diagnosis: Gastric Acid Dermatitis

After further discussion, the patient indicated that he had vomited during the night of alcohol consumption, and the vomitus remained on the affected areas until the next morning, indicating that excessive alcohol ingestion stimulated abundant secretion of gastric acid, which caused the symptoms. Additionally, the presence of clothing acted as a buffer in the unaffected areas, which helped make the final diagnosis of gastric acid dermatitis. The patient was treated with external application of recombinant bovine basic fibroblast growth factor gel (21,000 IU/5 g) once daily, and the lesions greatly improved within 7 days. The burning pain of the throat, stomach, and esophagus resolved after consultation with an otolaryngologist and a gastroenterologist.

Gastric acid dermatitis is a new term used to describe an acute skin burn caused by the patient's own gastric acid. Generally, the pH of human gastric acid is between 0.9 and 1.8 but will be diluted after eating and will gradually increase to approximately 3.5, which is not enough to induce burns on the skin.¹ In addition, the skin barrier is capable of preventing transient gastric acid corrosion.^2,3 However, the release of a large amount of gastric acid after excessive alcohol ingestion coupled with 1 night of lethargy left enough acid and time to induce skin burns in our patient.

Dermatitis caused by other allergic or chemical factors, such as Paederus dermatitis, was excluded, as the patient’s manifestation occurred during the inactive period of Paederus fuscipes. Furthermore, the patient denied any history of contact with chemicals in the last month. Food eruptions primarily manifest as systemic anaphylaxis with eruptive and pruritic rashes after consumption of seafood, eggs, milk, or other proteins, while alcoholic contact dermatitis is a form of irritating dermatitis that could be easily induced again by direct skin contact with alcohol.

Management of gastric acid dermatitis is similar to that for other chemical burns. Because scarring seldom occurs, the central issue is to restore the skin barrier as quickly as possible and to avoid or alleviate postinflammatory hyperpigmentation. Treatments to restore the skin barrier include recombinant bovine or human-derived basic fibroblast growth factor gel, moist exposed burn ointment, and medical sodium hyaluronate gelatin. To treat postinflammatory hyperpigmentation, some whitening agents such as compound superoxide dismutase arbutin cream and hydroquinone cream as well as the Q-switched Nd:YAG laser are effective to ameliorate the skin condition. If skin burns are on sun-exposed areas, photoprotection is necessary to prevent hyperpigmentation.

Acknowledgment—We thank the patient for granting permission to publish this information.

Frontal fibrosing alopecia (FFA) is an increasingly common diagnosis, especially in middle-aged women, and was first described by Kossard¹ in 1994. It is a variant of lichen planopilaris (LPP), a progressive scarring cicatricial alopecia that affects the frontotemporal area of the scalp, eyebrows, and sometimes even body hair.¹ Although its etiology remains unclear, genetic causes, drugs, hormones, and environmental exposures—including certain chemicals found in sunscreens—have been implicated in its pathogenesis.^2,3 An association between contact allergy to ingredients in personal care products and FFA diagnosis has been suggested; however, there is no evidence of causality to date. In this article, we highlight the potential relationship between contact allergy and FFA as well as clinical considerations for management.

Clinical Features and Diagnosis

Frontal fibrosing alopecia typically manifests with gradual symmetric recession of the frontal hairline leading to bandlike hair loss along the forehead, sometimes extending to the temporal region.⁴ Some patients may experience symptoms of scalp itching, burning, or tenderness that may precede or accompany the hair loss. Perifollicular erythema may be visible during the early stages and can be visualized on trichoscopy. The affected skin may appear pale and shiny and may have a smooth texture with a distinct lack of follicular openings. Aside from scalp involvement, other manifestations may include lichen planus pigmentosus, facial papules, body hair involvement, hypochromic lesions, diffuse redness on the face and neck, and prominent frontal veins.⁵ Although most FFA cases have characteristic clinical features and trichoscopic findings, biopsy for histopathologic examination is still recommended to confirm the diagnosis and ensure appropriate treatment.⁴ Classic histopathologic features include perifollicular lymphocytic inflammation, follicular destruction, and scarring.

Pathophysiology of FFA

The pathogenesis of FFA is thought to involve a variety of triggers, including immune-mediated inflammation, stress, genetics, hormones, and possibly environmental factors.⁶ Frontal fibrosing alopecia demonstrates considerable upregulation in cytotoxic helper T cells (T_H1) and IFN-γ activity resulting in epithelial hair follicle stem cell apoptosis and replacement of normal epithelial tissue with fibrous tissue.⁷ There is some suspicion of genetic susceptibility in the onset of FFA as suggested by familial reports and genome-wide association studies.^8-10 Hormonal and autoimmune factors also have been linked to FFA, including an increased risk for thyroid disease and the postmenopausal rise of androgen levels.⁶

Allergic Contact Dermatitis and FFA

Although they are 2 distinct conditions with differing etiologies, allergic contact dermatitis (ACD) and FFA may share environmental triggers, especially in susceptible individuals. This may support the coexistence and potential association between ACD and FFA.

In one case report, a woman who developed facial eczema followed by FFA showed positive patch tests to the UV filters drometrizole trisiloxane and ethylhexyl salicylate, which were listed as ingredients in her sunscreens. Avoidance of these allergens reportedly led to notable improvement of the symptoms.¹¹ Case-control studies have found an association between the use of facial sunscreen and risk for FFA.¹² A 2016 questionnaire that assessed a wide range of lifestyle, social, and medical factors related to FFA found that the use of sunscreens was significantly higher in patients with FFA than controls (P<.001), pointing to sunscreens as a potential contributing factor, but further research has been inconclusive. A higher frequency of positive patch tests to hydroperoxides of linalool and balsam of Peru (BoP) in patients with FFA have been documented; however, a direct cause cannot be established.²

In a 2020 prospective study conducted at multiple international centers, 65% (13/20) of FFA patients and 37.5% (9/24) of the control group had a positive patch test reaction to one or more allergens (P=.003). The most common allergens that were identified included cobalt chloride (positive in 35% [7/20] of patients with FFA), nickel sulfate (25% [5/20]), and potassium dichromate (15% [3/20]).¹³ In a recent 2-year cohort study of 42 patients with FFA who were referred for patch testing, the most common allergens included gallates, hydroperoxides of linalool, and other fragrances.¹⁴ After a 3-month period of allergen avoidance, 70% (29/42) of patients had decreased scalp erythema on examination, indicating that avoiding relevant allergens may reduce local inflammation. Furthermore, 76.2% (32/42) of patients with FFA showed delayed-type hypersensitivity to allergens found in daily personal care products such as shampoos, sunscreens, and moisturizers, among others.¹⁴ Notably, the study lacked a control group. A case-control study of 36 Hispanic women conducted in Mexico also resulted in 83.3% (15/18) of patients with FFA and 55.5% (10/18) of controls having at least 1 positive patch test; in the FFA group, these included iodopropynyl butylcarbamate (16.7% [3/18]) and propolis (16.7% [3/18]).¹⁵

Most recently, a retrospective study conducted by Shtaynberger et al¹⁶ included 12 patients with LPP or FFA diagnosed via clinical findings or biopsy. It also included an age- and temporally matched control group tested with identical allergens. Among the 12 patients who had FFA/LPP, all had at least 1 allergen identified on patch testing. The most common allergens identified were propolis (positive in 50% [6/12] of patients with FFA/LPP), fragrance mix I (16%), and methylisothiazolinone (16% [2/12]). Follow-up data were available for 9 of these patients, of whom 6 (66.7%) experienced symptom improvement after 6 months of allergen avoidance. Four (44.4%) patients experienced decreased follicular redness or scaling, 2 (22.2%) patients experienced improved scalp pain/itch, 2 (22.2%) patients had stable/improved hair density, and 1 (1.1%) patient had decreased hair shedding. Although this suggests an environmental trigger for FFA/LPP, the authors stated that changes in patient treatment plans could have contributed to their improvement. The study also was limited by its small size and its overall generalizability.¹⁶

These studies have underscored the significance of patch testing in individuals diagnosed with FFA and have identified common allergens prevalent in this patient population. They have suggested that patients with FFA are more likely to have positive patch tests, and in some cases patients could experience improvements in scalp pruritus and erythema with allergen avoidance; however, we emphasize that a causal association between contact allergy and FFA remains unproven to date.

Most Common Allergens Pertinent to FFA

Preservatives—In some studies, patients with FFA have had positive patch tests to preservatives such as gallates and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI).¹⁴ Gallates are antioxidants that are used in food preservation, pharmaceuticals, and cosmetics due to their ability to inhibit oxidation and rancidity of fats and oils.¹⁷ The most common gallates include propyl gallate, octyl gallate, and dodecyl gallate. Propyl gallate is utilized in some waxy or oily cosmetics and personal care items including sunscreens, shampoos, conditioners, bar soaps, facial cleansers, and moisturizers.¹⁸ Typically, if patients have a positive patch test to one gallate, they should be advised to avoid all gallate compounds, as they can cross-react.

Similarly, MCI/MI can prevent product degradation through their antibacterial and antifungal properties. This combination of MCI and MI is used as an effective method of prolonging the shelf life of cosmetic products and commonly is found in sunscreens, facial moisturizing creams, shampoos, and conditioners¹⁹; it is banned from use in leave-on products in the European Union and Canada due to increased rates of contact allergy.²⁰ In patients with FFA who commonly use facial sunscreen, preservatives can be a potential allergen exposure to consider.

Iodopropynyl butylcarbamate also is a preservative used in cosmetic formulations. Similar to MCI/MI, it is a potent fungicide and bactericide. This allergen can be found in hair care products, bodywashes, and other personal products.²¹

UV Light–Absorbing Agents—A systematic review and meta-analysis conducted in 2022 showed a significant (P<.001) association between sunscreen use and FFA.²² A majority of allergens identified on patch testing included UVA- and UVB-absorbing agents found in sunscreens and other products including cosmetics,^11,12 such as drometrizole trisiloxane, ethylhexyl salicylate, avobenzone, and benzophenone-4. Drometrizole trisiloxane is a photostabilizer and a broad-spectrum UV filter that is not approved for use in sunscreens in the United States.²³ It also is effective in stabilizing and preventing the degradation of avobenzone, a commonly used UVA filter.²⁴

Fragrances—Fragrances are present in nearly every personal and cosmetic product, sometimes even in those advertised as being “fragrance free.” Hydroperoxides of linalool, BoP, and fragrance mix are common allergens that are found in a variety of personal care products including perfumes, cosmetics, and even household cleaning supplies.²⁵ Simultaneous positive patch tests to BoP and fragrance mix are common due to shared components. Linalool can be found in various plants such as lavender, rose, bergamot, and jasmine.²⁶ Upon air exposure, linalool auto-oxidizes to form allergenic hydroperoxides of linalool. Among patients with FFA, positive patch test reactions to fragrance chemicals are common and could be attributed to the use of fragranced hair products and facial cosmetics.

Hair Dyes and Bleaches—Allergic reactions to hair dyes and bleaches can result in severe ACD of the head/neck and, in rare cases, scarring alopecia.²⁷ Chemicals found in these products include paraphenylenediamine (PPD) and ammonium persulfate. The most common hair dye allergen, PPD also is used in some rubbers and plastics. Ammonium persulfate is a chemical used in hair bleaches and to deodorize oils. One case study reported a patient with FFA who developed chemically induced vitiligo immediately after the use of a hair color product that contained PPD.²⁸ However, without patch testing to confirm the presence of contact allergy, other patient-specific and environmental risk factors could have contributed to FFA in this case.

In this endeavor to untangle the truth, it should be remembered that at the time of writing, the purported association between FFA and ACD remains debatable. Contact dermatitis specialists have voiced that the association between FFA and ACD, especially with regard to sunscreen, cannot be supported due to the lack of sufficient evidence.²⁹ A large majority of the research conducted on FFA and ACD is based on case reports and studies limited to a small sample size, and most of these patch test studies lack a control group. Felmingham et al³⁰ noted that the recent epidemiology of FFA aligns with increased sunscreen use. They also highlighted the limitations of the aforementioned studies, which include misclassification of exposures in the control group² and recall bias in questionnaire participants.^2,12 The most pressing limitation that permeates through most of these studies is the temporal ambiguity associated with sunscreen use. A study by Dhana et al³¹ failed to specify whether increased sunscreen use preceded the diagnosis of FFA or if it stems from the need to protect more exposed skin as a consequence of disease. Broad sunscreen avoidance due to concern for a possible association with hair loss could have detrimental health implications by increasing the risk for photodamage and skin cancer.

FFA Patch Testing

The avoidance of pertinent allergens could be effective in reducing local inflammation, pruritus, and erythema in FFA.^9,14,32 At our institution, we selectively patch test patients with FFA when there is a suspected contact allergy. Clinical features that may allude to a potential contact allergy include an erythematous or eczematous dermatitis or symptoms of pruritus along the scalp or eyebrows. If patients recall hair loss or symptoms after using a hair or facial product, then a potential contact allergy to these products could be considered. Patch testing in patients with FFA includes the North American 80 Comprehensive Series and the cosmetic and hairdresser supplemental series, as well as an additional customized panel of 8 allergens as determined by patch testing experts at the University of Massachusetts, Brigham and Women’s Hospital, and Massachusetts General Hospital (private email communication, November 2017). Patch test readings are performed at 48 and 96 or 120 hours. Using the American Contact Dermatitis Society’s Contact Allergen Management Program, patients are provided personalized safe product lists and avoidance strategies are discussed.

Final Interpretation

In a world where cosmetic products are ubiquitous, it is hard to define the potential role of contact allergens in the entangled pathogenesis of FFA and ACD. As evidenced by emerging literature that correlates the 2 conditions and their exacerbating factors, it is important for physicians to have a comprehensive diagnostic approach and heightened awareness for potential allergens at play in FFA (Table). The identification of certain chemicals and preservatives as potential triggers for FFA should emphasize the importance of patch testing in these patients; however, whether the positive reactions are relevant to the pathogenesis or disease course of FFA still is unknown. While these findings begin to unravel the intertwined causes of FFA and ACD, further research encompassing larger cohorts and prospective studies is imperative to solidify these associations, define concrete guidelines, and improve patient outcomes.

Frontal fibrosing alopecia (FFA) is an increasingly common diagnosis, especially in middle-aged women, and was first described by Kossard¹ in 1994. It is a variant of lichen planopilaris (LPP), a progressive scarring cicatricial alopecia that affects the frontotemporal area of the scalp, eyebrows, and sometimes even body hair.¹ Although its etiology remains unclear, genetic causes, drugs, hormones, and environmental exposures—including certain chemicals found in sunscreens—have been implicated in its pathogenesis.^2,3 An association between contact allergy to ingredients in personal care products and FFA diagnosis has been suggested; however, there is no evidence of causality to date. In this article, we highlight the potential relationship between contact allergy and FFA as well as clinical considerations for management.

Clinical Features and Diagnosis

Frontal fibrosing alopecia typically manifests with gradual symmetric recession of the frontal hairline leading to bandlike hair loss along the forehead, sometimes extending to the temporal region.⁴ Some patients may experience symptoms of scalp itching, burning, or tenderness that may precede or accompany the hair loss. Perifollicular erythema may be visible during the early stages and can be visualized on trichoscopy. The affected skin may appear pale and shiny and may have a smooth texture with a distinct lack of follicular openings. Aside from scalp involvement, other manifestations may include lichen planus pigmentosus, facial papules, body hair involvement, hypochromic lesions, diffuse redness on the face and neck, and prominent frontal veins.⁵ Although most FFA cases have characteristic clinical features and trichoscopic findings, biopsy for histopathologic examination is still recommended to confirm the diagnosis and ensure appropriate treatment.⁴ Classic histopathologic features include perifollicular lymphocytic inflammation, follicular destruction, and scarring.

Pathophysiology of FFA

The pathogenesis of FFA is thought to involve a variety of triggers, including immune-mediated inflammation, stress, genetics, hormones, and possibly environmental factors.⁶ Frontal fibrosing alopecia demonstrates considerable upregulation in cytotoxic helper T cells (T_H1) and IFN-γ activity resulting in epithelial hair follicle stem cell apoptosis and replacement of normal epithelial tissue with fibrous tissue.⁷ There is some suspicion of genetic susceptibility in the onset of FFA as suggested by familial reports and genome-wide association studies.^8-10 Hormonal and autoimmune factors also have been linked to FFA, including an increased risk for thyroid disease and the postmenopausal rise of androgen levels.⁶

Allergic Contact Dermatitis and FFA

Although they are 2 distinct conditions with differing etiologies, allergic contact dermatitis (ACD) and FFA may share environmental triggers, especially in susceptible individuals. This may support the coexistence and potential association between ACD and FFA.

In one case report, a woman who developed facial eczema followed by FFA showed positive patch tests to the UV filters drometrizole trisiloxane and ethylhexyl salicylate, which were listed as ingredients in her sunscreens. Avoidance of these allergens reportedly led to notable improvement of the symptoms.¹¹ Case-control studies have found an association between the use of facial sunscreen and risk for FFA.¹² A 2016 questionnaire that assessed a wide range of lifestyle, social, and medical factors related to FFA found that the use of sunscreens was significantly higher in patients with FFA than controls (P<.001), pointing to sunscreens as a potential contributing factor, but further research has been inconclusive. A higher frequency of positive patch tests to hydroperoxides of linalool and balsam of Peru (BoP) in patients with FFA have been documented; however, a direct cause cannot be established.²

In a 2020 prospective study conducted at multiple international centers, 65% (13/20) of FFA patients and 37.5% (9/24) of the control group had a positive patch test reaction to one or more allergens (P=.003). The most common allergens that were identified included cobalt chloride (positive in 35% [7/20] of patients with FFA), nickel sulfate (25% [5/20]), and potassium dichromate (15% [3/20]).¹³ In a recent 2-year cohort study of 42 patients with FFA who were referred for patch testing, the most common allergens included gallates, hydroperoxides of linalool, and other fragrances.¹⁴ After a 3-month period of allergen avoidance, 70% (29/42) of patients had decreased scalp erythema on examination, indicating that avoiding relevant allergens may reduce local inflammation. Furthermore, 76.2% (32/42) of patients with FFA showed delayed-type hypersensitivity to allergens found in daily personal care products such as shampoos, sunscreens, and moisturizers, among others.¹⁴ Notably, the study lacked a control group. A case-control study of 36 Hispanic women conducted in Mexico also resulted in 83.3% (15/18) of patients with FFA and 55.5% (10/18) of controls having at least 1 positive patch test; in the FFA group, these included iodopropynyl butylcarbamate (16.7% [3/18]) and propolis (16.7% [3/18]).¹⁵

Most recently, a retrospective study conducted by Shtaynberger et al¹⁶ included 12 patients with LPP or FFA diagnosed via clinical findings or biopsy. It also included an age- and temporally matched control group tested with identical allergens. Among the 12 patients who had FFA/LPP, all had at least 1 allergen identified on patch testing. The most common allergens identified were propolis (positive in 50% [6/12] of patients with FFA/LPP), fragrance mix I (16%), and methylisothiazolinone (16% [2/12]). Follow-up data were available for 9 of these patients, of whom 6 (66.7%) experienced symptom improvement after 6 months of allergen avoidance. Four (44.4%) patients experienced decreased follicular redness or scaling, 2 (22.2%) patients experienced improved scalp pain/itch, 2 (22.2%) patients had stable/improved hair density, and 1 (1.1%) patient had decreased hair shedding. Although this suggests an environmental trigger for FFA/LPP, the authors stated that changes in patient treatment plans could have contributed to their improvement. The study also was limited by its small size and its overall generalizability.¹⁶

These studies have underscored the significance of patch testing in individuals diagnosed with FFA and have identified common allergens prevalent in this patient population. They have suggested that patients with FFA are more likely to have positive patch tests, and in some cases patients could experience improvements in scalp pruritus and erythema with allergen avoidance; however, we emphasize that a causal association between contact allergy and FFA remains unproven to date.

Most Common Allergens Pertinent to FFA

Preservatives—In some studies, patients with FFA have had positive patch tests to preservatives such as gallates and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI).¹⁴ Gallates are antioxidants that are used in food preservation, pharmaceuticals, and cosmetics due to their ability to inhibit oxidation and rancidity of fats and oils.¹⁷ The most common gallates include propyl gallate, octyl gallate, and dodecyl gallate. Propyl gallate is utilized in some waxy or oily cosmetics and personal care items including sunscreens, shampoos, conditioners, bar soaps, facial cleansers, and moisturizers.¹⁸ Typically, if patients have a positive patch test to one gallate, they should be advised to avoid all gallate compounds, as they can cross-react.

Similarly, MCI/MI can prevent product degradation through their antibacterial and antifungal properties. This combination of MCI and MI is used as an effective method of prolonging the shelf life of cosmetic products and commonly is found in sunscreens, facial moisturizing creams, shampoos, and conditioners¹⁹; it is banned from use in leave-on products in the European Union and Canada due to increased rates of contact allergy.²⁰ In patients with FFA who commonly use facial sunscreen, preservatives can be a potential allergen exposure to consider.

Iodopropynyl butylcarbamate also is a preservative used in cosmetic formulations. Similar to MCI/MI, it is a potent fungicide and bactericide. This allergen can be found in hair care products, bodywashes, and other personal products.²¹

UV Light–Absorbing Agents—A systematic review and meta-analysis conducted in 2022 showed a significant (P<.001) association between sunscreen use and FFA.²² A majority of allergens identified on patch testing included UVA- and UVB-absorbing agents found in sunscreens and other products including cosmetics,^11,12 such as drometrizole trisiloxane, ethylhexyl salicylate, avobenzone, and benzophenone-4. Drometrizole trisiloxane is a photostabilizer and a broad-spectrum UV filter that is not approved for use in sunscreens in the United States.²³ It also is effective in stabilizing and preventing the degradation of avobenzone, a commonly used UVA filter.²⁴

Fragrances—Fragrances are present in nearly every personal and cosmetic product, sometimes even in those advertised as being “fragrance free.” Hydroperoxides of linalool, BoP, and fragrance mix are common allergens that are found in a variety of personal care products including perfumes, cosmetics, and even household cleaning supplies.²⁵ Simultaneous positive patch tests to BoP and fragrance mix are common due to shared components. Linalool can be found in various plants such as lavender, rose, bergamot, and jasmine.²⁶ Upon air exposure, linalool auto-oxidizes to form allergenic hydroperoxides of linalool. Among patients with FFA, positive patch test reactions to fragrance chemicals are common and could be attributed to the use of fragranced hair products and facial cosmetics.

Hair Dyes and Bleaches—Allergic reactions to hair dyes and bleaches can result in severe ACD of the head/neck and, in rare cases, scarring alopecia.²⁷ Chemicals found in these products include paraphenylenediamine (PPD) and ammonium persulfate. The most common hair dye allergen, PPD also is used in some rubbers and plastics. Ammonium persulfate is a chemical used in hair bleaches and to deodorize oils. One case study reported a patient with FFA who developed chemically induced vitiligo immediately after the use of a hair color product that contained PPD.²⁸ However, without patch testing to confirm the presence of contact allergy, other patient-specific and environmental risk factors could have contributed to FFA in this case.

In this endeavor to untangle the truth, it should be remembered that at the time of writing, the purported association between FFA and ACD remains debatable. Contact dermatitis specialists have voiced that the association between FFA and ACD, especially with regard to sunscreen, cannot be supported due to the lack of sufficient evidence.²⁹ A large majority of the research conducted on FFA and ACD is based on case reports and studies limited to a small sample size, and most of these patch test studies lack a control group. Felmingham et al³⁰ noted that the recent epidemiology of FFA aligns with increased sunscreen use. They also highlighted the limitations of the aforementioned studies, which include misclassification of exposures in the control group² and recall bias in questionnaire participants.^2,12 The most pressing limitation that permeates through most of these studies is the temporal ambiguity associated with sunscreen use. A study by Dhana et al³¹ failed to specify whether increased sunscreen use preceded the diagnosis of FFA or if it stems from the need to protect more exposed skin as a consequence of disease. Broad sunscreen avoidance due to concern for a possible association with hair loss could have detrimental health implications by increasing the risk for photodamage and skin cancer.

FFA Patch Testing

The avoidance of pertinent allergens could be effective in reducing local inflammation, pruritus, and erythema in FFA.^9,14,32 At our institution, we selectively patch test patients with FFA when there is a suspected contact allergy. Clinical features that may allude to a potential contact allergy include an erythematous or eczematous dermatitis or symptoms of pruritus along the scalp or eyebrows. If patients recall hair loss or symptoms after using a hair or facial product, then a potential contact allergy to these products could be considered. Patch testing in patients with FFA includes the North American 80 Comprehensive Series and the cosmetic and hairdresser supplemental series, as well as an additional customized panel of 8 allergens as determined by patch testing experts at the University of Massachusetts, Brigham and Women’s Hospital, and Massachusetts General Hospital (private email communication, November 2017). Patch test readings are performed at 48 and 96 or 120 hours. Using the American Contact Dermatitis Society’s Contact Allergen Management Program, patients are provided personalized safe product lists and avoidance strategies are discussed.

Final Interpretation

In a world where cosmetic products are ubiquitous, it is hard to define the potential role of contact allergens in the entangled pathogenesis of FFA and ACD. As evidenced by emerging literature that correlates the 2 conditions and their exacerbating factors, it is important for physicians to have a comprehensive diagnostic approach and heightened awareness for potential allergens at play in FFA (Table). The identification of certain chemicals and preservatives as potential triggers for FFA should emphasize the importance of patch testing in these patients; however, whether the positive reactions are relevant to the pathogenesis or disease course of FFA still is unknown. While these findings begin to unravel the intertwined causes of FFA and ACD, further research encompassing larger cohorts and prospective studies is imperative to solidify these associations, define concrete guidelines, and improve patient outcomes.

Frontal fibrosing alopecia (FFA) is an increasingly common diagnosis, especially in middle-aged women, and was first described by Kossard¹ in 1994. It is a variant of lichen planopilaris (LPP), a progressive scarring cicatricial alopecia that affects the frontotemporal area of the scalp, eyebrows, and sometimes even body hair.¹ Although its etiology remains unclear, genetic causes, drugs, hormones, and environmental exposures—including certain chemicals found in sunscreens—have been implicated in its pathogenesis.^2,3 An association between contact allergy to ingredients in personal care products and FFA diagnosis has been suggested; however, there is no evidence of causality to date. In this article, we highlight the potential relationship between contact allergy and FFA as well as clinical considerations for management.

Clinical Features and Diagnosis

Frontal fibrosing alopecia typically manifests with gradual symmetric recession of the frontal hairline leading to bandlike hair loss along the forehead, sometimes extending to the temporal region.⁴ Some patients may experience symptoms of scalp itching, burning, or tenderness that may precede or accompany the hair loss. Perifollicular erythema may be visible during the early stages and can be visualized on trichoscopy. The affected skin may appear pale and shiny and may have a smooth texture with a distinct lack of follicular openings. Aside from scalp involvement, other manifestations may include lichen planus pigmentosus, facial papules, body hair involvement, hypochromic lesions, diffuse redness on the face and neck, and prominent frontal veins.⁵ Although most FFA cases have characteristic clinical features and trichoscopic findings, biopsy for histopathologic examination is still recommended to confirm the diagnosis and ensure appropriate treatment.⁴ Classic histopathologic features include perifollicular lymphocytic inflammation, follicular destruction, and scarring.

Pathophysiology of FFA

The pathogenesis of FFA is thought to involve a variety of triggers, including immune-mediated inflammation, stress, genetics, hormones, and possibly environmental factors.⁶ Frontal fibrosing alopecia demonstrates considerable upregulation in cytotoxic helper T cells (T_H1) and IFN-γ activity resulting in epithelial hair follicle stem cell apoptosis and replacement of normal epithelial tissue with fibrous tissue.⁷ There is some suspicion of genetic susceptibility in the onset of FFA as suggested by familial reports and genome-wide association studies.^8-10 Hormonal and autoimmune factors also have been linked to FFA, including an increased risk for thyroid disease and the postmenopausal rise of androgen levels.⁶

Allergic Contact Dermatitis and FFA

Although they are 2 distinct conditions with differing etiologies, allergic contact dermatitis (ACD) and FFA may share environmental triggers, especially in susceptible individuals. This may support the coexistence and potential association between ACD and FFA.

In one case report, a woman who developed facial eczema followed by FFA showed positive patch tests to the UV filters drometrizole trisiloxane and ethylhexyl salicylate, which were listed as ingredients in her sunscreens. Avoidance of these allergens reportedly led to notable improvement of the symptoms.¹¹ Case-control studies have found an association between the use of facial sunscreen and risk for FFA.¹² A 2016 questionnaire that assessed a wide range of lifestyle, social, and medical factors related to FFA found that the use of sunscreens was significantly higher in patients with FFA than controls (P<.001), pointing to sunscreens as a potential contributing factor, but further research has been inconclusive. A higher frequency of positive patch tests to hydroperoxides of linalool and balsam of Peru (BoP) in patients with FFA have been documented; however, a direct cause cannot be established.²

In a 2020 prospective study conducted at multiple international centers, 65% (13/20) of FFA patients and 37.5% (9/24) of the control group had a positive patch test reaction to one or more allergens (P=.003). The most common allergens that were identified included cobalt chloride (positive in 35% [7/20] of patients with FFA), nickel sulfate (25% [5/20]), and potassium dichromate (15% [3/20]).¹³ In a recent 2-year cohort study of 42 patients with FFA who were referred for patch testing, the most common allergens included gallates, hydroperoxides of linalool, and other fragrances.¹⁴ After a 3-month period of allergen avoidance, 70% (29/42) of patients had decreased scalp erythema on examination, indicating that avoiding relevant allergens may reduce local inflammation. Furthermore, 76.2% (32/42) of patients with FFA showed delayed-type hypersensitivity to allergens found in daily personal care products such as shampoos, sunscreens, and moisturizers, among others.¹⁴ Notably, the study lacked a control group. A case-control study of 36 Hispanic women conducted in Mexico also resulted in 83.3% (15/18) of patients with FFA and 55.5% (10/18) of controls having at least 1 positive patch test; in the FFA group, these included iodopropynyl butylcarbamate (16.7% [3/18]) and propolis (16.7% [3/18]).¹⁵

Most recently, a retrospective study conducted by Shtaynberger et al¹⁶ included 12 patients with LPP or FFA diagnosed via clinical findings or biopsy. It also included an age- and temporally matched control group tested with identical allergens. Among the 12 patients who had FFA/LPP, all had at least 1 allergen identified on patch testing. The most common allergens identified were propolis (positive in 50% [6/12] of patients with FFA/LPP), fragrance mix I (16%), and methylisothiazolinone (16% [2/12]). Follow-up data were available for 9 of these patients, of whom 6 (66.7%) experienced symptom improvement after 6 months of allergen avoidance. Four (44.4%) patients experienced decreased follicular redness or scaling, 2 (22.2%) patients experienced improved scalp pain/itch, 2 (22.2%) patients had stable/improved hair density, and 1 (1.1%) patient had decreased hair shedding. Although this suggests an environmental trigger for FFA/LPP, the authors stated that changes in patient treatment plans could have contributed to their improvement. The study also was limited by its small size and its overall generalizability.¹⁶

These studies have underscored the significance of patch testing in individuals diagnosed with FFA and have identified common allergens prevalent in this patient population. They have suggested that patients with FFA are more likely to have positive patch tests, and in some cases patients could experience improvements in scalp pruritus and erythema with allergen avoidance; however, we emphasize that a causal association between contact allergy and FFA remains unproven to date.

Most Common Allergens Pertinent to FFA

Preservatives—In some studies, patients with FFA have had positive patch tests to preservatives such as gallates and methylchloroisothiazolinone/methylisothiazolinone (MCI/MI).¹⁴ Gallates are antioxidants that are used in food preservation, pharmaceuticals, and cosmetics due to their ability to inhibit oxidation and rancidity of fats and oils.¹⁷ The most common gallates include propyl gallate, octyl gallate, and dodecyl gallate. Propyl gallate is utilized in some waxy or oily cosmetics and personal care items including sunscreens, shampoos, conditioners, bar soaps, facial cleansers, and moisturizers.¹⁸ Typically, if patients have a positive patch test to one gallate, they should be advised to avoid all gallate compounds, as they can cross-react.

Similarly, MCI/MI can prevent product degradation through their antibacterial and antifungal properties. This combination of MCI and MI is used as an effective method of prolonging the shelf life of cosmetic products and commonly is found in sunscreens, facial moisturizing creams, shampoos, and conditioners¹⁹; it is banned from use in leave-on products in the European Union and Canada due to increased rates of contact allergy.²⁰ In patients with FFA who commonly use facial sunscreen, preservatives can be a potential allergen exposure to consider.

Iodopropynyl butylcarbamate also is a preservative used in cosmetic formulations. Similar to MCI/MI, it is a potent fungicide and bactericide. This allergen can be found in hair care products, bodywashes, and other personal products.²¹

UV Light–Absorbing Agents—A systematic review and meta-analysis conducted in 2022 showed a significant (P<.001) association between sunscreen use and FFA.²² A majority of allergens identified on patch testing included UVA- and UVB-absorbing agents found in sunscreens and other products including cosmetics,^11,12 such as drometrizole trisiloxane, ethylhexyl salicylate, avobenzone, and benzophenone-4. Drometrizole trisiloxane is a photostabilizer and a broad-spectrum UV filter that is not approved for use in sunscreens in the United States.²³ It also is effective in stabilizing and preventing the degradation of avobenzone, a commonly used UVA filter.²⁴

Fragrances—Fragrances are present in nearly every personal and cosmetic product, sometimes even in those advertised as being “fragrance free.” Hydroperoxides of linalool, BoP, and fragrance mix are common allergens that are found in a variety of personal care products including perfumes, cosmetics, and even household cleaning supplies.²⁵ Simultaneous positive patch tests to BoP and fragrance mix are common due to shared components. Linalool can be found in various plants such as lavender, rose, bergamot, and jasmine.²⁶ Upon air exposure, linalool auto-oxidizes to form allergenic hydroperoxides of linalool. Among patients with FFA, positive patch test reactions to fragrance chemicals are common and could be attributed to the use of fragranced hair products and facial cosmetics.

Hair Dyes and Bleaches—Allergic reactions to hair dyes and bleaches can result in severe ACD of the head/neck and, in rare cases, scarring alopecia.²⁷ Chemicals found in these products include paraphenylenediamine (PPD) and ammonium persulfate. The most common hair dye allergen, PPD also is used in some rubbers and plastics. Ammonium persulfate is a chemical used in hair bleaches and to deodorize oils. One case study reported a patient with FFA who developed chemically induced vitiligo immediately after the use of a hair color product that contained PPD.²⁸ However, without patch testing to confirm the presence of contact allergy, other patient-specific and environmental risk factors could have contributed to FFA in this case.

In this endeavor to untangle the truth, it should be remembered that at the time of writing, the purported association between FFA and ACD remains debatable. Contact dermatitis specialists have voiced that the association between FFA and ACD, especially with regard to sunscreen, cannot be supported due to the lack of sufficient evidence.²⁹ A large majority of the research conducted on FFA and ACD is based on case reports and studies limited to a small sample size, and most of these patch test studies lack a control group. Felmingham et al³⁰ noted that the recent epidemiology of FFA aligns with increased sunscreen use. They also highlighted the limitations of the aforementioned studies, which include misclassification of exposures in the control group² and recall bias in questionnaire participants.^2,12 The most pressing limitation that permeates through most of these studies is the temporal ambiguity associated with sunscreen use. A study by Dhana et al³¹ failed to specify whether increased sunscreen use preceded the diagnosis of FFA or if it stems from the need to protect more exposed skin as a consequence of disease. Broad sunscreen avoidance due to concern for a possible association with hair loss could have detrimental health implications by increasing the risk for photodamage and skin cancer.

FFA Patch Testing

The avoidance of pertinent allergens could be effective in reducing local inflammation, pruritus, and erythema in FFA.^9,14,32 At our institution, we selectively patch test patients with FFA when there is a suspected contact allergy. Clinical features that may allude to a potential contact allergy include an erythematous or eczematous dermatitis or symptoms of pruritus along the scalp or eyebrows. If patients recall hair loss or symptoms after using a hair or facial product, then a potential contact allergy to these products could be considered. Patch testing in patients with FFA includes the North American 80 Comprehensive Series and the cosmetic and hairdresser supplemental series, as well as an additional customized panel of 8 allergens as determined by patch testing experts at the University of Massachusetts, Brigham and Women’s Hospital, and Massachusetts General Hospital (private email communication, November 2017). Patch test readings are performed at 48 and 96 or 120 hours. Using the American Contact Dermatitis Society’s Contact Allergen Management Program, patients are provided personalized safe product lists and avoidance strategies are discussed.

Final Interpretation

In a world where cosmetic products are ubiquitous, it is hard to define the potential role of contact allergens in the entangled pathogenesis of FFA and ACD. As evidenced by emerging literature that correlates the 2 conditions and their exacerbating factors, it is important for physicians to have a comprehensive diagnostic approach and heightened awareness for potential allergens at play in FFA (Table). The identification of certain chemicals and preservatives as potential triggers for FFA should emphasize the importance of patch testing in these patients; however, whether the positive reactions are relevant to the pathogenesis or disease course of FFA still is unknown. While these findings begin to unravel the intertwined causes of FFA and ACD, further research encompassing larger cohorts and prospective studies is imperative to solidify these associations, define concrete guidelines, and improve patient outcomes.

The Diagnosis: Pellagra

The patient was diagnosed with pellagra based on the clinical and laboratory findings. He was discharged with nicotinamide 250 mg and folic acid 5 mg supplementation daily. After 3 months, all symptoms resolved.

Pellagra is a condition usually associated with the 4 Ds: dermatitis; diarrhea; dementia; and, if untreated, death.¹ The word pellagra is derived from the Italian terms pelle and agra, which mean skin and rough, respectively.² Spanish physician Gasper Casal first described pellagra in 1762 after observing the disease in poorer peasants in Asturias who mainly relied on maize and rarely consumed fresh meat.^1,2 Joseph Goldberger conducted research in the early 20th century, provoking the disease in jail prisoners by modifying their diets. However, it was not until 1926 that Goldberger discovered the true cause of the illness to be a poor diet and named what would become known as nicotinamide as the pellagra preventative factor.^1,2 Niacin (vitamin B3), the deficient molecule in pellagra, also is known as nicotinic acid, nicotinamide, or niacinamide. It is a water-soluble vitamin that is converted into nicotinamide-adenine-dinucleotide (NAD) and its phosphate NADP.^1,2 It has been hypothesized that pellagra symptoms arise from insufficient amounts of NAD and NADP, making the body unable to support cellular energy transfer processes.³

Pellagra manifests 50 to 60 days after starting a diet low in niacin. Niacin and nicotinamide are absorbed from the digested food to the stomach through a sodiumdependent mechanism, and then nicotinamide may be transformed into nicotinic acid with microsomal deamidation.³ Niacin may be obtained from one’s diet or produced from tryptophan. Foods with the highest amounts of niacin include liver, poultry, fish, eggs, milk, pork, mushrooms, avocados, almonds, and legumes.^1,3 Coffee also contains trigonelline, which may be transformed into nicotinic acid when roasted, increasing the niacin level by 30 times.³ Approximately 60 mg of dietary tryptophan is needed to produce up to 1 mg of niacin in the presence of B2 and B6 vitamins. This mechanism provides approximately half of the needs for niacin.3 Insufficient dietary intake of niacin or the essential amino acid tryptophan can cause pellagra (primary pellagra), which is a concern in resource-limited countries. Alternatively, the body may not be able to properly utilize niacin for metabolic processes (secondary pellagra), which occurs more frequently in developed countries.¹ Secondary pellagra also may be caused by alcoholism, colitis, cirrhosis, carcinoid tumors, Hartnup disease, or gastrointestinal tuberculosis, as these conditions prevent niacin from being consumed, absorbed, or processed. Certain medications can cause pellagra by interfering with the tryptophan-niacin pathway, including isoniazid, 5-fluorouracil, pyrazinamide, 6-mercaptopurine, hydantoins, ethionamide, phenobarbital, azathioprine, and chloramphenicol.²

The clinical manifestations of pellagra are diverse because it affects tissues with high turnover rates. Clinical features of pellagra include symmetric photosensitive skin eruptions, gastrointestinal tract symptoms, and neurologic and mental disorders.³ The first signs of pellagra may include muscle weakness, digestive concerns, and psychological or emotional discomfort.² Pellagra dermatitis manifests as an acute or intermittent, bilaterally symmetrical eruption on sun-exposed areas and is markedly distinct from healthy skin.³ Some individuals may experience vesiculation and bullae development (wet pellagra). The erythema is first brilliant red then turns into a cinnamon-brown color. Over time, the skin becomes thickened, scaly, cracked, and hyperpigmented.¹ The dryness of the skin likely is due to a remarkable decrease in wax ester and sebaceous gland atrophy seen on histopathology.⁴ Pellagra most frequently affects the back of the hands (77%–97% of cases), which can extend upward to create the so-called pellagra glove or gauntlet.³ It is common to see symmetrical eruptions in the shape of a butterfly following an anatomical pattern innervated by the trigeminal nerve, which resembles lupus erythematosus on the face. Another common manifestation is Casal necklace, a well-marginated eruption frequently seen on the front of the neck (Figure).² On the foot, lesions often do not develop close to the malleoli but rather terminate distally on the backs of the toes. Sometimes a boot pattern may form that covers the front and back of the leg.^1-3

The pathophysiology of photosensitivity in pellagra was hypothesized by Karthikeyan and Thappa.³ They discovered an excessive synthesis of a phototoxic substance, kynurenic acid, and a deficiency in urocanic acid, which normally protects the skin by absorbing light in the UVB range. Niacin deprivation leads to the production of kynurenic acid through the tryptophan-kynurenine-nicotinic acid pathway and reduces the amount of urocanic acid by affecting the enzyme histidase in the stratum corneum.^1-3 In one-third of patients, pellagra affects the oral mucosa, causing characteristic symptoms such as glossitis, angular stomatitis, and cheilitis.² In nearly 50% of patients, poor appetite, nausea, epigastric discomfort, diarrhea, and excessive salivation are present. Most of the gastrointestinal tract is affected by mucosal inflammation and atrophy, which can cause malnutrition and cachexia due to anorexia and malabsorptive diarrhea.² Headache, irritability, poor concentration, hallucinations, photophobia, tremor, and depression are some of the neuropsychiatric symptoms. Patients experience delirium and disorientation as pellagra progresses, followed by a comatose state and ultimately death.²

The patient’s history and physical examination are used to make the diagnosis, with particular attention to the patient’s dietary details. The diagnosis is made in part ex juvantibus by seeing how the patient responds to higher niacin doses. Anemia, hypoproteinemia, elevated blood calcium, reduced serum potassium and phosphorus, abnormal liver function tests, and elevated serum porphyrin levels also indicate pellagra. Niacin 300 mg in divided doses for up to 4 weeks has been recommended by the World Health Organization to treat pellagra.⁵ The flushing seen with niacin administration is not linked to the usage of nicotinamide. The recommended nicotinamide dosage for adults is 100 mg orally every 6 hours until most acute symptoms have disappeared, followed by oral administration of 50 mg every 8 to 12 hours until all skin lesions have healed.²

Among the differential diagnoses, necrolytic migratory erythema is characterized by an episodic eruption of crusted, erosive, annular erythematous plaques with blister development, which occurs in 70% of patients with glucagonoma syndrome. The perioral region, perineum, lower belly, thighs, and distal extremities are the usual locations.^6,7 Laboratory test results include elevated fasting serum glucagon (>1000 ng/L) and normocytic anemia, which aided in ruling out this diagnosis in our patient. Generalized acute cutaneous lupus erythematosus may appear as a broad morbilliform eruption. The hands frequently exhibit erythema and edema, especially across the dorsal and interphalangeal regions.8 Other typical findings of systemic lupus erythematosus such as antinuclear antibody were not seen in our patient, making this diagnosis unlikely. Porphyria cutanea tarda also must be considered in the differential diagnosis. The hepatic deficiency of uroporphyrinogen decarboxylase is the primary cause of this condition. Although it is characterized by blistering lesions, patients more frequently describe increased skin fragility in sun-exposed regions. Hypertrichosis, hyperpigmentation or hypopigmentation, hirsutism, or scarring may appear in the later stage of the disease.9 Phototoxic reaction was ruled out because the patient spent most of the time at home, and no new drugs had been prescribed in the previous months.

The Diagnosis: Pellagra

The patient was diagnosed with pellagra based on the clinical and laboratory findings. He was discharged with nicotinamide 250 mg and folic acid 5 mg supplementation daily. After 3 months, all symptoms resolved.

Pellagra is a condition usually associated with the 4 Ds: dermatitis; diarrhea; dementia; and, if untreated, death.¹ The word pellagra is derived from the Italian terms pelle and agra, which mean skin and rough, respectively.² Spanish physician Gasper Casal first described pellagra in 1762 after observing the disease in poorer peasants in Asturias who mainly relied on maize and rarely consumed fresh meat.^1,2 Joseph Goldberger conducted research in the early 20th century, provoking the disease in jail prisoners by modifying their diets. However, it was not until 1926 that Goldberger discovered the true cause of the illness to be a poor diet and named what would become known as nicotinamide as the pellagra preventative factor.^1,2 Niacin (vitamin B3), the deficient molecule in pellagra, also is known as nicotinic acid, nicotinamide, or niacinamide. It is a water-soluble vitamin that is converted into nicotinamide-adenine-dinucleotide (NAD) and its phosphate NADP.^1,2 It has been hypothesized that pellagra symptoms arise from insufficient amounts of NAD and NADP, making the body unable to support cellular energy transfer processes.³

Pellagra manifests 50 to 60 days after starting a diet low in niacin. Niacin and nicotinamide are absorbed from the digested food to the stomach through a sodiumdependent mechanism, and then nicotinamide may be transformed into nicotinic acid with microsomal deamidation.³ Niacin may be obtained from one’s diet or produced from tryptophan. Foods with the highest amounts of niacin include liver, poultry, fish, eggs, milk, pork, mushrooms, avocados, almonds, and legumes.^1,3 Coffee also contains trigonelline, which may be transformed into nicotinic acid when roasted, increasing the niacin level by 30 times.³ Approximately 60 mg of dietary tryptophan is needed to produce up to 1 mg of niacin in the presence of B2 and B6 vitamins. This mechanism provides approximately half of the needs for niacin.3 Insufficient dietary intake of niacin or the essential amino acid tryptophan can cause pellagra (primary pellagra), which is a concern in resource-limited countries. Alternatively, the body may not be able to properly utilize niacin for metabolic processes (secondary pellagra), which occurs more frequently in developed countries.¹ Secondary pellagra also may be caused by alcoholism, colitis, cirrhosis, carcinoid tumors, Hartnup disease, or gastrointestinal tuberculosis, as these conditions prevent niacin from being consumed, absorbed, or processed. Certain medications can cause pellagra by interfering with the tryptophan-niacin pathway, including isoniazid, 5-fluorouracil, pyrazinamide, 6-mercaptopurine, hydantoins, ethionamide, phenobarbital, azathioprine, and chloramphenicol.²

The clinical manifestations of pellagra are diverse because it affects tissues with high turnover rates. Clinical features of pellagra include symmetric photosensitive skin eruptions, gastrointestinal tract symptoms, and neurologic and mental disorders.³ The first signs of pellagra may include muscle weakness, digestive concerns, and psychological or emotional discomfort.² Pellagra dermatitis manifests as an acute or intermittent, bilaterally symmetrical eruption on sun-exposed areas and is markedly distinct from healthy skin.³ Some individuals may experience vesiculation and bullae development (wet pellagra). The erythema is first brilliant red then turns into a cinnamon-brown color. Over time, the skin becomes thickened, scaly, cracked, and hyperpigmented.¹ The dryness of the skin likely is due to a remarkable decrease in wax ester and sebaceous gland atrophy seen on histopathology.⁴ Pellagra most frequently affects the back of the hands (77%–97% of cases), which can extend upward to create the so-called pellagra glove or gauntlet.³ It is common to see symmetrical eruptions in the shape of a butterfly following an anatomical pattern innervated by the trigeminal nerve, which resembles lupus erythematosus on the face. Another common manifestation is Casal necklace, a well-marginated eruption frequently seen on the front of the neck (Figure).² On the foot, lesions often do not develop close to the malleoli but rather terminate distally on the backs of the toes. Sometimes a boot pattern may form that covers the front and back of the leg.^1-3

The pathophysiology of photosensitivity in pellagra was hypothesized by Karthikeyan and Thappa.³ They discovered an excessive synthesis of a phototoxic substance, kynurenic acid, and a deficiency in urocanic acid, which normally protects the skin by absorbing light in the UVB range. Niacin deprivation leads to the production of kynurenic acid through the tryptophan-kynurenine-nicotinic acid pathway and reduces the amount of urocanic acid by affecting the enzyme histidase in the stratum corneum.^1-3 In one-third of patients, pellagra affects the oral mucosa, causing characteristic symptoms such as glossitis, angular stomatitis, and cheilitis.² In nearly 50% of patients, poor appetite, nausea, epigastric discomfort, diarrhea, and excessive salivation are present. Most of the gastrointestinal tract is affected by mucosal inflammation and atrophy, which can cause malnutrition and cachexia due to anorexia and malabsorptive diarrhea.² Headache, irritability, poor concentration, hallucinations, photophobia, tremor, and depression are some of the neuropsychiatric symptoms. Patients experience delirium and disorientation as pellagra progresses, followed by a comatose state and ultimately death.²

The patient’s history and physical examination are used to make the diagnosis, with particular attention to the patient’s dietary details. The diagnosis is made in part ex juvantibus by seeing how the patient responds to higher niacin doses. Anemia, hypoproteinemia, elevated blood calcium, reduced serum potassium and phosphorus, abnormal liver function tests, and elevated serum porphyrin levels also indicate pellagra. Niacin 300 mg in divided doses for up to 4 weeks has been recommended by the World Health Organization to treat pellagra.⁵ The flushing seen with niacin administration is not linked to the usage of nicotinamide. The recommended nicotinamide dosage for adults is 100 mg orally every 6 hours until most acute symptoms have disappeared, followed by oral administration of 50 mg every 8 to 12 hours until all skin lesions have healed.²

Among the differential diagnoses, necrolytic migratory erythema is characterized by an episodic eruption of crusted, erosive, annular erythematous plaques with blister development, which occurs in 70% of patients with glucagonoma syndrome. The perioral region, perineum, lower belly, thighs, and distal extremities are the usual locations.^6,7 Laboratory test results include elevated fasting serum glucagon (>1000 ng/L) and normocytic anemia, which aided in ruling out this diagnosis in our patient. Generalized acute cutaneous lupus erythematosus may appear as a broad morbilliform eruption. The hands frequently exhibit erythema and edema, especially across the dorsal and interphalangeal regions.8 Other typical findings of systemic lupus erythematosus such as antinuclear antibody were not seen in our patient, making this diagnosis unlikely. Porphyria cutanea tarda also must be considered in the differential diagnosis. The hepatic deficiency of uroporphyrinogen decarboxylase is the primary cause of this condition. Although it is characterized by blistering lesions, patients more frequently describe increased skin fragility in sun-exposed regions. Hypertrichosis, hyperpigmentation or hypopigmentation, hirsutism, or scarring may appear in the later stage of the disease.9 Phototoxic reaction was ruled out because the patient spent most of the time at home, and no new drugs had been prescribed in the previous months.

The Diagnosis: Pellagra

The patient was diagnosed with pellagra based on the clinical and laboratory findings. He was discharged with nicotinamide 250 mg and folic acid 5 mg supplementation daily. After 3 months, all symptoms resolved.

Pellagra is a condition usually associated with the 4 Ds: dermatitis; diarrhea; dementia; and, if untreated, death.¹ The word pellagra is derived from the Italian terms pelle and agra, which mean skin and rough, respectively.² Spanish physician Gasper Casal first described pellagra in 1762 after observing the disease in poorer peasants in Asturias who mainly relied on maize and rarely consumed fresh meat.^1,2 Joseph Goldberger conducted research in the early 20th century, provoking the disease in jail prisoners by modifying their diets. However, it was not until 1926 that Goldberger discovered the true cause of the illness to be a poor diet and named what would become known as nicotinamide as the pellagra preventative factor.^1,2 Niacin (vitamin B3), the deficient molecule in pellagra, also is known as nicotinic acid, nicotinamide, or niacinamide. It is a water-soluble vitamin that is converted into nicotinamide-adenine-dinucleotide (NAD) and its phosphate NADP.^1,2 It has been hypothesized that pellagra symptoms arise from insufficient amounts of NAD and NADP, making the body unable to support cellular energy transfer processes.³

Pellagra manifests 50 to 60 days after starting a diet low in niacin. Niacin and nicotinamide are absorbed from the digested food to the stomach through a sodiumdependent mechanism, and then nicotinamide may be transformed into nicotinic acid with microsomal deamidation.³ Niacin may be obtained from one’s diet or produced from tryptophan. Foods with the highest amounts of niacin include liver, poultry, fish, eggs, milk, pork, mushrooms, avocados, almonds, and legumes.^1,3 Coffee also contains trigonelline, which may be transformed into nicotinic acid when roasted, increasing the niacin level by 30 times.³ Approximately 60 mg of dietary tryptophan is needed to produce up to 1 mg of niacin in the presence of B2 and B6 vitamins. This mechanism provides approximately half of the needs for niacin.3 Insufficient dietary intake of niacin or the essential amino acid tryptophan can cause pellagra (primary pellagra), which is a concern in resource-limited countries. Alternatively, the body may not be able to properly utilize niacin for metabolic processes (secondary pellagra), which occurs more frequently in developed countries.¹ Secondary pellagra also may be caused by alcoholism, colitis, cirrhosis, carcinoid tumors, Hartnup disease, or gastrointestinal tuberculosis, as these conditions prevent niacin from being consumed, absorbed, or processed. Certain medications can cause pellagra by interfering with the tryptophan-niacin pathway, including isoniazid, 5-fluorouracil, pyrazinamide, 6-mercaptopurine, hydantoins, ethionamide, phenobarbital, azathioprine, and chloramphenicol.²

The clinical manifestations of pellagra are diverse because it affects tissues with high turnover rates. Clinical features of pellagra include symmetric photosensitive skin eruptions, gastrointestinal tract symptoms, and neurologic and mental disorders.³ The first signs of pellagra may include muscle weakness, digestive concerns, and psychological or emotional discomfort.² Pellagra dermatitis manifests as an acute or intermittent, bilaterally symmetrical eruption on sun-exposed areas and is markedly distinct from healthy skin.³ Some individuals may experience vesiculation and bullae development (wet pellagra). The erythema is first brilliant red then turns into a cinnamon-brown color. Over time, the skin becomes thickened, scaly, cracked, and hyperpigmented.¹ The dryness of the skin likely is due to a remarkable decrease in wax ester and sebaceous gland atrophy seen on histopathology.⁴ Pellagra most frequently affects the back of the hands (77%–97% of cases), which can extend upward to create the so-called pellagra glove or gauntlet.³ It is common to see symmetrical eruptions in the shape of a butterfly following an anatomical pattern innervated by the trigeminal nerve, which resembles lupus erythematosus on the face. Another common manifestation is Casal necklace, a well-marginated eruption frequently seen on the front of the neck (Figure).² On the foot, lesions often do not develop close to the malleoli but rather terminate distally on the backs of the toes. Sometimes a boot pattern may form that covers the front and back of the leg.^1-3

The pathophysiology of photosensitivity in pellagra was hypothesized by Karthikeyan and Thappa.³ They discovered an excessive synthesis of a phototoxic substance, kynurenic acid, and a deficiency in urocanic acid, which normally protects the skin by absorbing light in the UVB range. Niacin deprivation leads to the production of kynurenic acid through the tryptophan-kynurenine-nicotinic acid pathway and reduces the amount of urocanic acid by affecting the enzyme histidase in the stratum corneum.^1-3 In one-third of patients, pellagra affects the oral mucosa, causing characteristic symptoms such as glossitis, angular stomatitis, and cheilitis.² In nearly 50% of patients, poor appetite, nausea, epigastric discomfort, diarrhea, and excessive salivation are present. Most of the gastrointestinal tract is affected by mucosal inflammation and atrophy, which can cause malnutrition and cachexia due to anorexia and malabsorptive diarrhea.² Headache, irritability, poor concentration, hallucinations, photophobia, tremor, and depression are some of the neuropsychiatric symptoms. Patients experience delirium and disorientation as pellagra progresses, followed by a comatose state and ultimately death.²

The patient’s history and physical examination are used to make the diagnosis, with particular attention to the patient’s dietary details. The diagnosis is made in part ex juvantibus by seeing how the patient responds to higher niacin doses. Anemia, hypoproteinemia, elevated blood calcium, reduced serum potassium and phosphorus, abnormal liver function tests, and elevated serum porphyrin levels also indicate pellagra. Niacin 300 mg in divided doses for up to 4 weeks has been recommended by the World Health Organization to treat pellagra.⁵ The flushing seen with niacin administration is not linked to the usage of nicotinamide. The recommended nicotinamide dosage for adults is 100 mg orally every 6 hours until most acute symptoms have disappeared, followed by oral administration of 50 mg every 8 to 12 hours until all skin lesions have healed.²

Among the differential diagnoses, necrolytic migratory erythema is characterized by an episodic eruption of crusted, erosive, annular erythematous plaques with blister development, which occurs in 70% of patients with glucagonoma syndrome. The perioral region, perineum, lower belly, thighs, and distal extremities are the usual locations.^6,7 Laboratory test results include elevated fasting serum glucagon (>1000 ng/L) and normocytic anemia, which aided in ruling out this diagnosis in our patient. Generalized acute cutaneous lupus erythematosus may appear as a broad morbilliform eruption. The hands frequently exhibit erythema and edema, especially across the dorsal and interphalangeal regions.8 Other typical findings of systemic lupus erythematosus such as antinuclear antibody were not seen in our patient, making this diagnosis unlikely. Porphyria cutanea tarda also must be considered in the differential diagnosis. The hepatic deficiency of uroporphyrinogen decarboxylase is the primary cause of this condition. Although it is characterized by blistering lesions, patients more frequently describe increased skin fragility in sun-exposed regions. Hypertrichosis, hyperpigmentation or hypopigmentation, hirsutism, or scarring may appear in the later stage of the disease.9 Phototoxic reaction was ruled out because the patient spent most of the time at home, and no new drugs had been prescribed in the previous months.

TOPLINE:

Allergens were present in more than half of evaluable over-the-counter (OTC) topical scar products, study finds. 

METHODOLOGY:

• OTC topical scar treatments have the potential to cause an allergic reaction, but the prevalence of North American Contact Dermatitis Group (NACDG) core allergens in these products is unclear.
• Researchers used the word scar in a query of Amazon.com and four other retail websites to identify topical scar products for consumers and noted the list of ingredients.
• The investigators also surveyed the American Contact Dermatitis Society’s Contact Allergen Management Program (CAMP), a resource that helps patients with allergies find personal care products that are safe to use, for pertinent products.

TAKEAWAY: 

• The search query identified 156 products. Of these, 119 (76.2%) were gels, creams, or oils and 37 (23.7%) were sheets, strips, or tape.
• Of the 125 products that had a list of ingredients, 69 (55.2%) contained at least one NACDG allergen and 45 (36%) contained more than one.
• The top six most common allergens listed in the ingredients were fragrance (16.8%), phenoxyethanol (16.8%), parabens (14.4%), panthenol (12.8%), sodium benzoate (9.60%), and ethylhexylglycerin (8%).
• Analysis of CAMP revealed that the program only had five unique scar products in its list, suggesting that CAMP might not be a reliable source of scar product information for patients with known allergies to pertinent NACDG allergens.

IN PRACTICE:

“Patients can consider trying a ‘use test’ on the inner forearm before applying to the surgical site,” the authors wrote. “It may reveal they are sensitive or sensitized by a product. 

SOURCE:

First author Meera Kattapuram, MD, of the Department of Internal Medicine at Mount Sinai Hospital, New York, led the study, published in the February issue of Dermatologic Surgery.  

LIMITATIONS:

Limitations include the selection of five retailers and the top 100 products from each website and the potential for ingredient list inaccuracies. 

DISCLOSURES:

The authors reported having no financial conflicts of interest. The research was supported by a grant from the National Institutes of Health/National Cancer Institute. 

A version of this article appeared on Medscape.com.

TOPLINE:

Allergens were present in more than half of evaluable over-the-counter (OTC) topical scar products, study finds. 

METHODOLOGY:

• OTC topical scar treatments have the potential to cause an allergic reaction, but the prevalence of North American Contact Dermatitis Group (NACDG) core allergens in these products is unclear.
• Researchers used the word scar in a query of Amazon.com and four other retail websites to identify topical scar products for consumers and noted the list of ingredients.
• The investigators also surveyed the American Contact Dermatitis Society’s Contact Allergen Management Program (CAMP), a resource that helps patients with allergies find personal care products that are safe to use, for pertinent products.

TAKEAWAY: 

• The search query identified 156 products. Of these, 119 (76.2%) were gels, creams, or oils and 37 (23.7%) were sheets, strips, or tape.
• Of the 125 products that had a list of ingredients, 69 (55.2%) contained at least one NACDG allergen and 45 (36%) contained more than one.
• The top six most common allergens listed in the ingredients were fragrance (16.8%), phenoxyethanol (16.8%), parabens (14.4%), panthenol (12.8%), sodium benzoate (9.60%), and ethylhexylglycerin (8%).
• Analysis of CAMP revealed that the program only had five unique scar products in its list, suggesting that CAMP might not be a reliable source of scar product information for patients with known allergies to pertinent NACDG allergens.

IN PRACTICE:

“Patients can consider trying a ‘use test’ on the inner forearm before applying to the surgical site,” the authors wrote. “It may reveal they are sensitive or sensitized by a product. 

SOURCE:

First author Meera Kattapuram, MD, of the Department of Internal Medicine at Mount Sinai Hospital, New York, led the study, published in the February issue of Dermatologic Surgery.  

LIMITATIONS:

Limitations include the selection of five retailers and the top 100 products from each website and the potential for ingredient list inaccuracies. 

DISCLOSURES:

The authors reported having no financial conflicts of interest. The research was supported by a grant from the National Institutes of Health/National Cancer Institute. 

A version of this article appeared on Medscape.com.

TOPLINE:

Allergens were present in more than half of evaluable over-the-counter (OTC) topical scar products, study finds. 

METHODOLOGY:

• OTC topical scar treatments have the potential to cause an allergic reaction, but the prevalence of North American Contact Dermatitis Group (NACDG) core allergens in these products is unclear.
• Researchers used the word scar in a query of Amazon.com and four other retail websites to identify topical scar products for consumers and noted the list of ingredients.
• The investigators also surveyed the American Contact Dermatitis Society’s Contact Allergen Management Program (CAMP), a resource that helps patients with allergies find personal care products that are safe to use, for pertinent products.

TAKEAWAY: 

• The search query identified 156 products. Of these, 119 (76.2%) were gels, creams, or oils and 37 (23.7%) were sheets, strips, or tape.
• Of the 125 products that had a list of ingredients, 69 (55.2%) contained at least one NACDG allergen and 45 (36%) contained more than one.
• The top six most common allergens listed in the ingredients were fragrance (16.8%), phenoxyethanol (16.8%), parabens (14.4%), panthenol (12.8%), sodium benzoate (9.60%), and ethylhexylglycerin (8%).
• Analysis of CAMP revealed that the program only had five unique scar products in its list, suggesting that CAMP might not be a reliable source of scar product information for patients with known allergies to pertinent NACDG allergens.

IN PRACTICE:

“Patients can consider trying a ‘use test’ on the inner forearm before applying to the surgical site,” the authors wrote. “It may reveal they are sensitive or sensitized by a product. 

SOURCE:

First author Meera Kattapuram, MD, of the Department of Internal Medicine at Mount Sinai Hospital, New York, led the study, published in the February issue of Dermatologic Surgery.  

LIMITATIONS:

Limitations include the selection of five retailers and the top 100 products from each website and the potential for ingredient list inaccuracies. 

DISCLOSURES:

The authors reported having no financial conflicts of interest. The research was supported by a grant from the National Institutes of Health/National Cancer Institute. 

A version of this article appeared on Medscape.com.